def __init__(self, message_listener, message_descriptor, key_checker,
               entry_descriptor):
    """
    Args:
      message_listener: A MessageListener implementation.
        The ScalarMap will call this object's Modified() method when it
        is modified.
      key_checker: A type_checkers.ValueChecker instance to run on keys
        inserted into this container.
      value_checker: A type_checkers.ValueChecker instance to run on values
        inserted into this container.
      entry_descriptor: The MessageDescriptor of a map entry: key and value.
    """
    self._message_listener = message_listener
    self._message_descriptor = message_descriptor
    self._key_checker = key_checker
    self._entry_descriptor = entry_descriptor
    self._values = {}

    Args:
      message_listener: A MessageListener implementation.
        The ScalarMap will call this object's Modified() method when it
        is modified.
      key_checker: A type_checkers.ValueChecker instance to run on keys
        inserted into this container.
      value_checker: A type_checkers.ValueChecker instance to run on values
        inserted into this container.
      entry_descriptor: The MessageDescriptor of a map entry: key and value.
    
deps/protobuf/python/google/protobuf/internal/containers.py