def authGSSClientStep(context, challenge, **kwargs):
    """
    Processes a single GSSAPI client-side step using the supplied server data.

    @param context: The context object returned from L{authGSSClientInit}.

    @param challenge: A string containing the base64-encoded server data (which
        may be empty for the first step).

    @param channel_bindings: Optional channel bindings to bind onto the auth
        request. This struct can be built using :{channelBindings}
        and if not specified it will pass along GSS_C_NO_CHANNEL_BINDINGS as
        a default.

    @return: A result code (see above).
    """
