Change the status of the specified signing certificate from
        Active to Inactive or vice versa.

        If the user_name is not specified, it is determined implicitly based
        on the AWS Access Key ID used to sign the request.

        :type cert_id: string
        :param cert_id: The ID of the signing certificate

        :type status: string
        :param status: Either Active or Inactive.

        :type user_name: string
        :param user_name: The username of the user

def update_signing_cert(self, cert_id, status, user_name=None):
        """
        Change the status of the specified signing certificate from
        Active to Inactive or vice versa.

        If the user_name is not specified, it is determined implicitly based
        on the AWS Access Key ID used to sign the request.

        :type cert_id: string
        :param cert_id: The ID of the signing certificate

        :type status: string
        :param status: Either Active or Inactive.

        :type user_name: string
        :param user_name: The username of the user
        """
        params = {'CertificateId' : cert_id,
                  'Status' : status}
        if user_name:
            params['UserName'] = user_name
        return self.get_response('UpdateSigningCertificate', params)