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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def updateEnterpriseUser(self, username, idpUsername):
 """ This operation allows an administrator to update the idpUsername for an enterprise user in the portal. This is used when migrating from accounts used with web-tier authentication to SAML authentication. Parameters: username - username of the enterprise account idpUsername - username used by the SAML identity provider """

        params = {
            "f" : "json",
            "username" : username,
            "idpUsername" : idpUsername
        }
        url = self._url + "/users/updateEnterpriseUser"
        return self._post(url=url,
                          param_dict=params,
                          proxy_url=self._proxy_url,
                          proxy_port=self._proxy_port)