def get_line_number_from_function(fn):
    """Get the line number for the end of the function signature.

    The function signature can be farther down when the parameter
    list is split across multiple lines.

    Args:
        fn: The function from which we are getting the line number.

    Returns:
        The line number for the start of the docstring for this
        function.

    """
    line_number = fn.lineno
    if hasattr(fn, 'args') and fn.args.args:
        last_arg = fn.args.args[-1]
        line_number = last_arg.lineno
    return line_number
