def MappingStart(self, event, loader):
    self._HandleAnchor(event)
    token, parent = self._top






    if token == _TOKEN_KEY:
      token, parent = self._stack[-2]
    mapping = self._builder.BuildMapping(parent)
    self._HandleValue(mapping)
    self._Push(_TOKEN_MAPPING, mapping)
Start of mapping scope.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/yaml_builder.py/BuilderHandler.MappingStart