import re


def is_file_path(line_str):
    """
    Test if `line_str` is a file path.

    >>> is_file_path('/Users/me/code/OpenSearchResult/open_search_result.py:')
    True
    >>> is_file_path('C:\\Users\\me\\test.txt:')
    True
    >>> is_file_path('5: def parse_line_number(line_str):')
    False
    """
    return re.match("^(/|\w:\\\).*:$", line_str) is not None