# Buggy code
def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
    """Return a list of :class:`ProtoComment` objects parsed from the given `prefix`."""
    result: List[ProtoComment] = []
    if not prefix or "#" not in prefix:
        return result

    consumed = 0
    nlines = 0
    ignored_lines = 0
    for index, line in enumerate(prefix.split("\n")):
        consumed += len(line) + 1  # adding the length of the split '\n'
        line = line.lstrip()
        if not line:
            nlines += 1
        if not line.startswith("#"):
            # Escaped newlines outside of a comment are not really newlines at
            # all. We treat a single-line comment following an escaped newline
            # as a simple trailing comment.
            if line.endswith("\\"):
                ignored_lines += 1
            continue

        if index == ignored_lines and not is_endmarker:
            comment_type = token.COMMENT  # simple trailing comment
        else:
            comment_type = STANDALONE_COMMENT
        comment = make_comment(line)
        result.append(
            ProtoComment(
                type=comment_type, value=comment, newlines=nlines, consumed=consumed
            )
        )
        nlines = 0
    return result


# Traceback (libcst._nodes.base.CSTValidationError)
fuzz run-test: commands[2] | coverage run fuzz.py
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
<string>:1: SyntaxWarning: "is" with a literal. Did you mean "=="?
Highest target scores:
5  (label='(hypothesmith) number of unique ast node types')
9  (label='(hypothesmith) instructions in bytecode')
10  (label='(hypothesmith from_node) number of unique ast node types')
13  (label='(hypothesmith) total number of ast nodes')
35  (label='(hypothesmith from_node) total number of ast nodes')
48  (label='(hypothesmith from_node) instructions in bytecode')

Traceback (most recent call last):
File "<string>", line 7, in __init__
File "/home/cooper/repos/black/.tox/fuzz/lib/python3.9/site-packages/libcst/_nodes/base.py", line 115, in __post_init__
self._validate()
File "/home/cooper/repos/black/.tox/fuzz/lib/python3.9/site-packages/libcst/_nodes/expression.py", line 1148, in _validate
raise CSTValidationError(
File "<string>", line None
libcst._nodes.base.CSTValidationError: Must have at least one space around comparison operator.

# Fixed code
def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
    """Return a list of :class:`ProtoComment` objects parsed from the given `prefix`."""
    result: List[ProtoComment] = []
    if not prefix or "#" not in prefix:
        return result

    consumed = 0
    nlines = 0
    ignored_lines = 0
    for index, line in enumerate(re.split("\r?\n", prefix)):
        consumed += len(line) + 1  # adding the length of the split '\n'
        line = line.lstrip()
        if not line:
            nlines += 1
        if not line.startswith("#"):
            # Escaped newlines outside of a comment are not really newlines at
            # all. We treat a single-line comment following an escaped newline
            # as a simple trailing comment.
            if line.endswith("\\"):
                ignored_lines += 1
            continue

        if index == ignored_lines and not is_endmarker:
            comment_type = token.COMMENT  # simple trailing comment
        else:
            comment_type = STANDALONE_COMMENT
        comment = make_comment(line)
        result.append(
            ProtoComment(
                type=comment_type, value=comment, newlines=nlines, consumed=consumed
            )
        )
        nlines = 0
    return result