code: def list_docs(self, options=None):
          
          if options is None:
              raise ValueError("Please pass in an options dict")
  
          default_options = {
              "page": 1,
              "per_page": 100,
              "raise_exception_on_failure": False,
              "user_credentials": self.api_key,
          }
          options = dict(list(default_options.items()) + list(options.items()))
          raise_exception_on_failure = options.pop("raise_exception_on_failure")
  
          resp = requests.get(
              "%sdocs" % (self._url), params=options, timeout=self._timeout
          )
  
          if raise_exception_on_failure and resp.status_code != 200:
              raise DocumentListingFailure(resp.content, resp.status_code)
          return resp
docs: Return list of previously created documents.