<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def all(self, fields=None, include_fields=True, page=None, per_page=None, extra_params=None):
 """Retrieves a list of all the applications. Important: The client_secret and encryption_key attributes can only be retrieved with the read:client_keys scope. Args: fields (list of str, optional):
 A list of fields to include or exclude from the result (depending on include_fields). Empty to retrieve all fields. include_fields (bool, optional):
 True if the fields specified are to be included in the result, False otherwise. page (int):
 The result's page number (zero based). per_page (int, optional):
 The amount of entries per page. extra_params (dictionary, optional):
 The extra parameters to add to the request. The fields, include_fields, page and per_page values specified as parameters take precedence over the ones defined here. See: https://auth0.com/docs/api/management/v2#!/Clients/get_clients """

        params = extra_params or {}
        params['fields'] = fields and ','.join(fields) or None
        params['include_fields'] = str(include_fields).lower()
        params['page'] = page
        params['per_page'] = per_page

        return self.client.get(self._url(), params=params)