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Solve the following problem using Python, implementing the functions described below, one line at a time
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<USER_TASK:>
Description:
 def create(self, username, **kwargs):
 """ Create a user in Keycloak http://www.keycloak.org/docs-api/3.4/rest-api/index.html#_users_resource :param str username: :param object credentials: (optional) :param str first_name: (optional) :param str last_name: (optional) :param str email: (optional) :param boolean enabled: (optional) """

        payload = OrderedDict(username=username)

        for key in USER_KWARGS:
            from keycloak.admin.clientroles import to_camel_case
            if key in kwargs:
                payload[to_camel_case(key)] = kwargs[key]

        return self._client.post(
            url=self._client.get_full_url(
                self.get_path('collection', realm=self._realm_name)
            ),
            data=json.dumps(payload, sort_keys=True)
        )