docs: def sign_execute_cancellation(cancellation_params, key_pair):
      """
      Function to sign the parameters required to execute a cancellation request on the Switcheo Exchange.
      Execution of this function is as follows::
  
          sign_execute_cancellation(cancellation_params=signable_params, key_pair=key_pair)
  
      The expected return result for this function is as follows::
  
          {
              'signature': '6a40d6c011b7517f8fd3f2d0de32dd486adfd1d424d06d56c80eb....'
          }
  
      :param cancellation_params: Parameters the Switcheo Exchange returns from the create cancellation.
      :type cancellation_params: dict
      :param key_pair: The KeyPair for the wallet being used to sign deposit message.
      :type key_pair: KeyPair
      :return: Dictionary of signed message to send to the Switcheo API.
      """
      signature = sign_transaction(transaction=cancellation_params['transaction'],
                                   private_key_hex=private_key_to_hex(key_pair=key_pair))
      return {'signature': signature}