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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def sign(self, request, consumer, token):
 """Builds the base signature string."""

        key, raw = self.signing_base(request, consumer, token)

        hashed = hmac.new(key, raw, sha1)

        # Calculate the digest base 64.
        return binascii.b2a_base64(hashed.digest())[:-1]