Return the path to the source file of the current frames' caller.

def caller_path(steps=1):
    """Return the path to the source file of the current frames' caller."""
    frame = sys._getframe(steps + 1)

    try:
        path = os.path.dirname(frame.f_code.co_filename)
    finally:
        del frame

    if not path:
        path = os.getcwd()

    return os.path.realpath(path)