docs: def filter(self, field, operator, value):
          """ Add a query filter to be applied to the next API list call for this resource.
              :param field: Field name to filter by
              :type field: str
              :param operator: Operator value
              :type operator: str
              :param value: Value of filter
              :type value: str
              :param object_type: Optional. Checks field for object association
              :type object_type: str
  
              Known Filters:
                  Question                    [question(2)]                   surveyresponse
                  Question Option             [question(2), option(10001)]    surveyresponse
                  Date Submitted              datesubmitted                   surveyresponse
                  Is Test Data                istestdata                      surveyresponse
                  Status                      status                          surveyresponse
                  Contact ID                  contact_id                      surveyresponse
                  Creation Time               createdon                       survey
                  Last Modified Time          modifiedon                      survey
                  Survey Title                title                           survey
                  Type of Project             subtype                         survey
                  Team Survey Belongs To      team                            survey
                  Status                      status                          survey
                  Type of Link                type                            surveycampaign
                  Name of Link                name                            surveycampaign
                  Secure / Unsecure Link      ssl                             surveycampaign
                  Link Created Date           datecreated                     surveycampaign
                  Link Last Modified Date     datemodified                    surveycampaign
  
  
              Known Operators:
                  =           Is equal to (==)
                  <>          Is equal to (!=)
                  IS NULL     Value is not answered or is blank
                  IS NOT NULL Value is answered or is not blank
                  in          Value is in comma separated list
  
              Unknown Operators:
                  Not officially mentioned in documentation, but may work.
                  ==
                  !=
                  >=
                  <=
                  >
                  <
          """
          instance = copy(self)
  
          i = len(instance._filters)
          instance._filters.append({
              'filter[field][%d]' % i: str(field),
              'filter[operator][%d]' % i: str(operator),
              'filter[value][%d]' % i: str(value),
          })
          return instance