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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 validate_host_parameters(self, host_list, remote_user):
        '''
        Validate and set the host list and remote user parameters.
        '''
        if host_list is None:
            host_list = self.host_list

        if remote_user is None:
            remote_user = self.remote_user

        if host_list is None or remote_user is None:
            print "Host list [%s], remote user [%s] are required" % \
                  (host_list, remote_user)
            return (None, None)

        return (host_list, remote_user)