code: async def createClaimRequest(self, schemaId: ID, proverId=None,
                                   reqNonRevoc=True) -> ClaimRequest:
          
          await self._genMasterSecret(schemaId)
          U = await self._genU(schemaId)
          Ur = None if not reqNonRevoc else await self._genUr(schemaId)
          proverId = proverId if proverId else self.proverId
          return ClaimRequest(userId=proverId, U=U, Ur=Ur)
docs: Creates a claim request to the issuer.
  
          :param schemaId: The schema ID (reference to claim
          definition schema)
          :param proverId: a prover ID request a claim for (if None then
          the current prover default ID is used)
          :param reqNonRevoc: whether to request non-revocation claim
          :return: Claim Request