Retrieves the specified policy document for the specified user.

        :type user_name: string
        :param user_name: The name of the user the policy is associated with.

        :type policy_name: string
        :param policy_name: The policy document to get.

def get_user_policy(self, user_name, policy_name):
        """
        Retrieves the specified policy document for the specified user.

        :type user_name: string
        :param user_name: The name of the user the policy is associated with.

        :type policy_name: string
        :param policy_name: The policy document to get.
        
        """
        params = {'UserName' : user_name,
                  'PolicyName' : policy_name}
        return self.get_response('GetUserPolicy', params, verb='POST')