def METHOD_NAME(cls):
    """
    Find the stack frame of the caller so that we can note the source
    file name, line number and function name.
    """
    f = currentframe()
    # On some versions of IronPython, currentframe() returns None if
    # IronPython isn't run with -X:Frames.
    if f is not None:
        f = f.f_back
    rv = "(unknown file)", 0, "(unknown function)"
    while hasattr(f, "f_code"):
        co = f.f_code
        filename = os.path.normcase(co.co_filename)
        if filename == _srcfile:
            f = f.f_back
            continue
        rv = (co.co_filename, f.f_lineno, co.co_name)
        break
    return rv