torchgen.model.FunctionSchema.parse fails with following ops' schema 
Labels: triaged, module: codegen

### 🐛 Describe the bug

Is this expected? 
Do we want to handle following case? 


```
aten::to.prim_Device(Tensor(a) self, Device? device, int? dtype=None, bool non_blocking=False, bool copy=False) -> Tensor(b|a)
unrecognized alias annotation b|a
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1223, in parse
    returns = parse_returns(return_decl)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2578, in parse_returns
    return tuple(Return.parse(arg) for arg in return_decl.split(", "))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2578, in <genexpr>
    return tuple(Return.parse(arg) for arg in return_decl.split(", "))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1900, in parse
    annotation = Annotation.parse(match.group(1))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1588, in parse
    assert m is not None, f"unrecognized alias annotation {ann}"
AssertionError: unrecognized alias annotation b|a

prims::as_strided(Tensor(a!) a, int[] size, int[] stride, int storage_offset) -> Tensor(a!)
If you have a schema with mutable positional args, we expect them to not be returned. schema: prims::as_strided(Tensor(a!) a, int[] size, int[] stride, int storage_offset) -> Tensor(a!)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1224, in parse
    r = FunctionSchema(name=name, arguments=arguments, returns=returns)
  File "<string>", line 6, in __init__
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1245, in __post_init__
    assert not any(
AssertionError: If you have a schema with mutable positional args, we expect them to not be returned. schema: prims::as_strided(Tensor(a!) a, int[] size, int[] stride, int storage_offset) -> Tensor(a!)

prims::copy_to(Tensor(a!) a, Tensor b) -> Tensor(a!)
If you have a schema with mutable positional args, we expect them to not be returned. schema: prims::copy_to(Tensor(a!) a, Tensor b) -> Tensor(a!)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1224, in parse
    r = FunctionSchema(name=name, arguments=arguments, returns=returns)
  File "<string>", line 6, in __init__
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1245, in __post_init__
    assert not any(
AssertionError: If you have a schema with mutable positional args, we expect them to not be returned. schema: prims::copy_to(Tensor(a!) a, Tensor b) -> Tensor(a!)

prims::resize(Tensor(a!) a, int[] shape) -> Tensor(a!)
If you have a schema with mutable positional args, we expect them to not be returned. schema: prims::resize(Tensor(a!) a, int[] shape) -> Tensor(a!)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1224, in parse
    r = FunctionSchema(name=name, arguments=arguments, returns=returns)
  File "<string>", line 6, in __init__
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1245, in __post_init__
    assert not any(
AssertionError: If you have a schema with mutable positional args, we expect them to not be returned. schema: prims::resize(Tensor(a!) a, int[] shape) -> Tensor(a!)

aten::add.t(t[] a, t[] b) -> t[]
unrecognized type t
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1636, in _parse
    return BaseType(BaseTy[t])
  File "/fsx/users/bahuang/conda/envs/pt_dev/lib/python3.9/enum.py", line 432, in __getitem__
    return cls._member_map_[name]
KeyError: 't'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1845, in parse
    type = Type.parse(type_s)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1629, in _parse
    return ListType(elem=Type.parse(m.group(1)), size=size)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1638, in _parse
    raise RuntimeError(f"unrecognized type {t}")
RuntimeError: unrecognized type t

aten::eq.enum(AnyEnumType a, AnyEnumType b) -> bool
unrecognized type AnyEnumType
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1636, in _parse
    return BaseType(BaseTy[t])
  File "/fsx/users/bahuang/conda/envs/pt_dev/lib/python3.9/enum.py", line 432, in __getitem__
    return cls._member_map_[name]
KeyError: 'AnyEnumType'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1845, in parse
    type = Type.parse(type_s)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1638, in _parse
    raise RuntimeError(f"unrecognized type {t}")
RuntimeError: unrecognized type AnyEnumType

aten::mul.left_t(t[] l, int n) -> t[]
unrecognized type t
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1636, in _parse
    return BaseType(BaseTy[t])
  File "/fsx/users/bahuang/conda/envs/pt_dev/lib/python3.9/enum.py", line 432, in __getitem__
    return cls._member_map_[name]
KeyError: 't'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1845, in parse
    type = Type.parse(type_s)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1629, in _parse
    return ListType(elem=Type.parse(m.group(1)), size=size)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1638, in _parse
    raise RuntimeError(f"unrecognized type {t}")
RuntimeError: unrecognized type t

aten::mul.right_(int n, t[] l) -> t[]
unrecognized type t
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1636, in _parse
    return BaseType(BaseTy[t])
  File "/fsx/users/bahuang/conda/envs/pt_dev/lib/python3.9/enum.py", line 432, in __getitem__
    return cls._member_map_[name]
KeyError: 't'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1845, in parse
    type = Type.parse(type_s)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1629, in _parse
    return ListType(elem=Type.parse(m.group(1)), size=size)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1638, in _parse
    raise RuntimeError(f"unrecognized type {t}")
RuntimeError: unrecognized type t

aten::ne.enum(AnyEnumType a, AnyEnumType b) -> bool
unrecognized type AnyEnumType
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1636, in _parse
    return BaseType(BaseTy[t])
  File "/fsx/users/bahuang/conda/envs/pt_dev/lib/python3.9/enum.py", line 432, in __getitem__
    return cls._member_map_[name]
KeyError: 'AnyEnumType'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1845, in parse
    type = Type.parse(type_s)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1617, in parse
    r = Type._parse(t)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1638, in _parse
    raise RuntimeError(f"unrecognized type {t}")
RuntimeError: unrecognized type AnyEnumType

aten::rot90(Tensor self, int k=1, int[] dims=[0, 1]) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_fft2(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_fft2.out(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None, *, Tensor(a!) out) -> Tensor(a!)
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_ifft2(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_ifft2.out(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None, *, Tensor(a!) out) -> Tensor(a!)
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_rfft2(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_rfft2.out(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None, *, Tensor(a!) out) -> Tensor(a!)
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_irfft2(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_irfft2.out(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None, *, Tensor(a!) out) -> Tensor(a!)
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_hfft2(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_hfft2.out(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None, *, Tensor(a!) out) -> Tensor(a!)
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_ihfft2(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None) -> Tensor
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

aten::fft_ihfft2.out(Tensor self, int[1]? s=None, int[1] dim=[-2, -1], str? norm=None, *, Tensor(a!) out) -> Tensor(a!)
not enough values to unpack (expected 2, got 1)
Traceback (most recent call last):
  File "/fsx/users/bahuang/repos/pytorch_fsx/torch/_ops.py", line 39, in __init__
    self._parsed_schema: FunctionSchema = FunctionSchema.parse(str(schema))
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1222, in parse
    arguments = Arguments.parse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2183, in parse
    positional, kwarg_only, out = Arguments._preparse(args)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 2154, in _preparse
    parg = Argument.parse(arg)
  File "/fsx/users/bahuang/repos/pytorch_fsx/torchgen/model.py", line 1824, in parse
    type_and_annot, name_and_default = arg.rsplit(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)
```

### Versions

master 

cc @ezyang @bhosmer @bdhirsh