def sign_execute_cancellation(cancellation_params, private_key):
    """
    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, private_key=eth_private_key)

    The expected return result for this function is as follows::

        {
            'signature': '0x65986ed2cb631d4999ce8b9c895a43f....'
        }

    :param cancellation_params: Parameters the Switcheo Exchange returns from the create cancellation.
    :type cancellation_params: dict
    :param private_key: The Ethereum private key to sign the deposit parameters.
    :type private_key: str
    :return: Dictionary of signed message to send to the Switcheo API.
    """
    cancellation_sha256 = cancellation_params['transaction']['sha256']
    signed_sha256 = binascii.hexlify(
        Account.signHash(cancellation_sha256, private_key=private_key)['signature']).decode()
    return {'signature': '0x' + signed_sha256}
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, private_key=eth_private_key)

    The expected return result for this function is as follows::

        {
            'signature': '0x65986ed2cb631d4999ce8b9c895a43f....'
        }

    :param cancellation_params: Parameters the Switcheo Exchange returns from the create cancellation.
    :type cancellation_params: dict
    :param private_key: The Ethereum private key to sign the deposit parameters.
    :type private_key: str
    :return: Dictionary of signed message to send to the Switcheo API.