class_docstr: Abstract base class for protocol messages.
  
  Protocol message classes are almost always generated by the protocol
  compiler.  These generated types subclass Message and implement the methods
  shown below.
docstr: Checks if a certain field is set for the message.
  
  For a oneof group, checks if any field inside is set. Note that if the
  field_name is not defined in the message descriptor, :exc:`ValueError` will
  be raised.
  
  Args:
    field_name (str): The name of the field to check for presence.
  
  Returns:
    bool: Whether a value has been set for the named field.
  
  Raises:
    ValueError: if the `field_name` is not a member of this message.
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code: def HasField(self, field_name):
      """Checks if a certain field is set for the message.
  
      For a oneof group, checks if any field inside is set. Note that if the
      field_name is not defined in the message descriptor, :exc:`ValueError` will
      be raised.
  
      Args:
        field_name (str): The name of the field to check for presence.
  
      Returns:
        bool: Whether a value has been set for the named field.
  
      Raises:
        ValueError: if the `field_name` is not a member of this message.
      """
      raise NotImplementedError
  
label_desc: Use image node_id 17 for calling the Message obj's underlying member method code with example usage: obj.HasField(field_name) without return types