'Get dictionary representation of argument arrrays.
Returns
arg_dict : dict of str to NDArray
The dictionary that maps the names of arguments to NDArrays.
Raises
ValueError : if there are duplicated names in the arguments.'

@property
def arg_dict(self):

    if (self._arg_dict is None):
        self._arg_dict = Executor._get_dict(self._symbol.list_arguments(), self.arg_arrays)
    return self._arg_dict
