def __setitem__(self, key, value):
    is_addition = self.Get(key) is None
    if is_addition and len(self) >= self.MAX_LEN:
      raise appinfo_errors.TooManyHttpHeaders(
          'Tried to add another header when the current set of HTTP headers'
          ' already has the maximum allowed number of headers, %d.'
          % HttpHeadersDict.MAX_LEN)
    super(HttpHeadersDict, self).__setitem__(key, value)
dataset/ETHPy150Open GoogleCloudPlatform/python-compat-runtime/appengine-compat/exported_appengine_sdk/google/appengine/api/appinfo.py/HttpHeadersDict.__setitem__/original