code: def add_fields(self, fields):
          
          for field in fields:
              cls = field.__class__
              try:
                  container = FieldsContainer.class_container[cls]
              except KeyError:
                  raise ValueError('Object of type %s is an invalid field' % cls)
              getattr(self, container).append(field)
docs: Add the fields to their corresponding container.
          
          `fields` is an iterable of field objects from osrframework.thirdparties.pipl_com.lib.fields.