def append_default_to_args(arguments, default_arguments):
    """Returns a dictionary with the default arguments appended to the arguments.

    Example:
      1) All default arguments are appended.
        Input:
          arguments = {"argument1": "42", "argument2": "binary"}
          default_arguments = {"argument3": "hello", "argument4": "world"}
          append_default_to_args(arguments, default_arguments)

        Output:
            {"argument1": "42", "argument2": "binary", "argument3": "hello",
             "argument4": "world"}
      2) Some default arguments are appended.
        Input:
          arguments = {"argument1": "42", "argument2": "binary"}
          default_arguments = {"argument2": "hello", "argument3": "world"}
          append_default_to_args(arguments, default_arguments)

        Output:
            {"argument1": "42", "argument2": "binary", "argument3": "world"}
      3) No default arguments are appended.
        Input:
          arguments = {"argument1": "42", "argument2": "binary"}
          default_arguments = {"argument1": "hello", "argument2": "world"}
          append_default_to_args(arguments, default_arguments)

        Output:
            {"argument1": "42", "argument2": "binary"}

    Args:
      arguments: A dictionary of arguments where the key is the argument name
        and the value is the value of the argument.
      default_arguments: A dictionary of arguments where the key is the argument
        name and the value is the value of the argument.
    Returns:
      A newly created dictionary with the default_arguments append to the
      arguments.
    """

    # Append to arguments
    my_args = dict(arguments)
    for key in default_arguments.keys():
        my_args.setdefault(key, default_arguments[key])
    return my_args