Given an array of integers arr. Return the number of sub-arrays with odd sum.
As the answer may grow large, the answer must be computed modulo 10^9 + 7.
 
Example 1:
Input: arr = [1,3,5]
Output: 4
Explanation: All sub-arrays are [[1],[1,3],[1,3,5],[3],[3,5],[5]]
All sub-arrays sum are [1,4,9,3,8,5].
Odd sums are [1,9,3,5] so the answer is 4.

Example 2:
Input: arr = [2,4,6]
Output: 0
Explanation: All sub-arrays are [[2],[2,4],[2,4,6],[4],[4,6],[6]]
All sub-arrays sum are [2,6,12,4,10,6].
All sub-arrays have even sum and the answer is 0.

Example 3:
Input: arr = [1,2,3,4,5,6,7]
Output: 16

Example 4:
Input: arr = [100,100,99,99]
Output: 4

Example 5:
Input: arr = [7]
Output: 1

 
Constraints:

1 <= arr.length <= 10^5
1 <= arr[i] <= 100

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = "# class Solution:\n#     def numOfSubarrays(self, arr: List[int]) -> int:\n#         odd = 0\n#         even = 0\n#         n = len(arr)\n#         sumlist = [0]*n\n#         output = 0\n#         for i in range(n-1, -1, -1):\n#             if i != n-1:\n#                 sumlist[i] += arr[i] + sumlist[i + 1] \n#             else:\n#                 sumlist[i] += arr[i]\n#             if sumlist[i] % 2 == 0:\n#                 output += odd\n#                 even += 1\n#             else:\n#                 output += 1\n#                 output += even\n#                 odd += 1\n#             output %= (10**9 + 7)\n#         return output\n\n# class Solution:\n#     def numOfSubarrays(self, A):\n#         # prefix sum means the sum of all numbers up to that index\n#         # count = [the number of even prefix sums, the number of odd prefix sums]\n#         # we start with 1 even prefix sum because 0 is even\n#         count = [1, 0]\n#         # initialize the current prefix sum (cur) as being even and initialize the result as 0\n#         cur = res = 0\n#         # go through each of the numbers in the array\n#         for a in A:\n#             # see if the next number is odd (which is what a&1 is doing since it's a bitwise AND operator), and use the exclusion OR operator to see if the current number and the previous number add up to being even (0) or odd (1)\n#             # this can also be written as cur = (cur + (a % 2))%2\n#             cur ^= a & 1\n#             # if the prefix sum is even, then add the number of odd prefix sums to the results. If the prefix sum is odd, then add the number of even prefix sums to the result.\n#             res += count[1 - cur]\n#             # increase the counter for the number of even or odd prefix sums seen so far\n#             count[cur] += 1\n#         return res % (10**9 + 7)\n\nclass Solution:\n    def numOfSubarrays(self, arr: List[int]) -> int:\n        res = odd = even = 0\n        for x in arr:\n            even += 1\n            if x % 2:\n                odd, even = even, odd\n            res = (res + odd) % 1000000007             \n        return res         "
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'numOfSubarrays'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 5332