code: def find_by_id(self, custom_field, params={}, **options): 
          
          path = "/custom_fields/%s" % (custom_field)
          return self.client.get(path, params, **options)
docs: Returns the complete definition of a custom field's metadata.
  
          Parameters
          ----------
          custom_field : {Id} Globally unique identifier for the custom field.
          [params] : {Object} Parameters for the request