code: def find_by(cls, payload, require=False):
          
          if not isinstance(payload, dict):
              raise ValueError("The 'payload' parameter must be provided a dictionary object.")
          url = os.path.join(cls.URL, "find_by")
          payload = {"find_by": payload}
          cls.debug_logger.debug("Searching Pulsar {} for {}".format(cls.__name__, json.dumps(payload, indent=4)))
          res = requests.post(url=url, json=payload, headers=HEADERS, verify=False)
          #cls.write_response_html_to_file(res,"bob.html")
          res.raise_for_status()
          res_json = res.json()
          if res_json:
             try:
                 res_json = res_json[cls.MODEL_NAME]
             except KeyError:
                 # Key won't be present if there isn't a serializer for it on the server.
                 pass
          else:
              if require:
                  raise RecordNotFound("Can't find any {} records with search criteria: '{}'.".format(cls.__name__, payload))
          return res_json
docs: Searches the model in question by AND joining the query parameters.
  
          Implements a Railsy way of looking for a record using a method by the same name and passing
          in the query as a dict. as well. Only the first hit is returned, and there is no particular
          ordering specified in the server-side API method.
  
          Args:
              payload: `dict`. The attributes of a record to restrict the search to.
              require: `bool`. True means to raise a `pulsarpy.models.RecordNotFound` exception if no
                  record is found.
  
          Returns:
              `dict`: The JSON serialization of the record, if any, found by the API call.
              `None`: If the API call didnt' return any results. 
  
          Raises:
              `pulsarpy.models.RecordNotFound`: No records were found, and the `require` parameter is
                  True.