code: def add_custom_field_setting(self, project, params={}, **options): 
          
          path = "/projects/%s/addCustomFieldSetting" % (project)
          return self.client.post(path, params, **options)
docs: Create a new custom field setting on the project.
  
          Parameters
          ----------
          project : {Id} The project to associate the custom field with
          [data] : {Object} Data for the request
            - custom_field : {Id} The id of the custom field to associate with this project.
            - [is_important] : {Boolean} Whether this field should be considered important to this project.
            - [insert_before] : {Id} An id of a Custom Field Settings on this project, before which the new Custom Field Settings will be added.
            `insert_before` and `insert_after` parameters cannot both be specified.
            - [insert_after] : {Id} An id of a Custom Field Settings on this project, after which the new Custom Field Settings will be added.
            `insert_before` and `insert_after` parameters cannot both be specified.