function enumeration() {
	// NOTE: the following should match the C `input_casting_policies.h` enumeration!!!!
	return {
		'none': 0,
		'promoted': 1,
		'accumulation': 2,
		'output': 3
	};
}
Returns an object mapping supported policy strings to enumeration constants.

## Notes

-   Downstream consumers of this mapping should **not** rely on specific integer values (e.g., `NONE == 0`). Instead, the object should be used in an opaque manner.
-   The main purpose of this function is JavaScript and C inter-operation of ndarray objects.

@private
@returns {Object} object mapping supported policies to enumeration constants

@example
var table = enumeration();
// returns <Object>