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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 has_permission(self, request, view):
 """ If the JWT has a user filter, verify that the filtered user value matches the user in the URL. """

        user_filter = self._get_user_filter(request)
        if not user_filter:
            # no user filters are present in the token to limit access
            return True

        username_param = get_username_param(request)
        allowed = user_filter == username_param
        if not allowed:
            log.warning(
                u"Permission JwtHasUserFilterForRequestedUser: user_filter %s doesn't match username %s.",
                user_filter,
                username_param,
            )
        return allowed