<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def submit_sample_url(self, url, params={}, _extra_params={}):
 """ Submit a sample at a given URL for analysis. """

        self._check_user_parameters(params)
        params = copy.copy(params)
        params['sample-url'] = url
        return self._submit(params, _extra_params=_extra_params)