<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def signing_base(self, request, consumer, token):
 """Concatenates the consumer key and secret with the token's secret."""

        sig = '%s&' % escape(consumer.secret)
        if token:
            sig = sig + escape(token.secret)
        return sig, sig