<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sign(self, data):
 """ Create an URL-safe, signed token from ``data``. """

        data = signing.b64_encode(data).decode()
        return self.signer.sign(data)