def same_signature(a, b):
    """Check whether a arginfo and b arginfo are the same signature.

    Actual names of arguments may differ. Default arguments may be
    different.
    """
    a_args = set(a.args)
    b_args = set(b.args)
    return len(a_args) == len(b_args
        ) and a.varargs == b.varargs and a.varkw == b.varkw
