Retrieve the NumPy's `dtype` for a given atomic data type.

def _get_atomic_dtype(data_type):
    """Retrieve the NumPy's `dtype` for a given atomic data type."""
    atomic_type = getattr(data_type, 'type', None)
    if atomic_type is not None:
        return atomic_type

    return _PREDEFINED_ATOMIC_NUMPY_TYPES[_find_base_type(data_type)]