def addheader(self, key, value):
    prev = self.dict.get(key)
    if prev is None:
      self.dict[key] = value
    else:
      combined = ", ".join((prev, value))
      self.dict[key] = combined
Add header for field key handling repeats.
dataset/ETHPy150Open GoogleCloudPlatform/python-compat-runtime/appengine-compat/exported_appengine_sdk/google/appengine/dist27/gae_override/httplib.py/HTTPMessage.addheader