def is_requirement(line):
    """
    Return True if the requirement line is a package requirement.

    Returns:
        bool: True if the line is not blank, a comment, a URL, or an included file
    """
    return not (
        line == '' or
        line.startswith('-r') or
        line.startswith('#') or
        line.startswith('-e') or
        line.startswith('git+') or
        line.startswith('-c')
    )