Approves the credential offer and submits a credential request. The result will be a credential stored in the prover's wallet.
        :param connection: connection to submit request from
        :param payment_handle: currently unused
        :return:
        Example:
        connection = await Connection.create(source_id)
        await connection.connect(phone_number)
        credential = await Credential.create(source_id, offer)
        await credential.send_request(connection, 0)

async def send_request(self, connection: Connection, payment_handle: int):
        """
        Approves the credential offer and submits a credential request. The result will be a credential stored in the prover's wallet.
        :param connection: connection to submit request from
        :param payment_handle: currently unused
        :return:
        Example:
        connection = await Connection.create(source_id)
        await connection.connect(phone_number)
        credential = await Credential.create(source_id, offer)
        await credential.send_request(connection, 0)
        """
        if not hasattr(Credential.send_request, "cb"):
            self.logger.debug("vcx_credential_send_request: Creating callback")
            Credential.send_request.cb = create_cb(CFUNCTYPE(None, c_uint32, c_uint32))

        c_credential_handle = c_uint32(self.handle)
        c_connection_handle = c_uint32(connection.handle)
        c_payment = c_uint32(payment_handle)

        await do_call('vcx_credential_send_request',
                      c_credential_handle,
                      c_connection_handle,
                      c_payment,
                      Credential.send_request.cb)