function check() {
	var MASK;
	var mask;
	var bool;
	var old;
	var i;

	MASK = proc.umask();
	bool = true;

	for ( i = 100; i < 200; i++ ) {
		old = proc.umask();

		// Should return an integer-valued number:
		if ( typeof old !== 'number' ) {
			bool = false;
			break;
		}

		// Attempt to update the mask:
		mask = proc.umask( i );

		// Should have returned the previous mask:
		if ( mask !== old ) {
			bool = false;
			break;
		}
		// Should return the current mask:
		if ( proc.umask() !== i ) {
			bool = false;
			break;
		}
	}
	proc.umask( MASK ); // restore
	return bool;
}
Checks whether the built-in `process.umask` exhibits expected behavior.

## Notes

-   In certain environments on Windows, `process.umask` does not seem to behave as expected (e.g., a mask cannot be set). This function is indicated to "sniff" this behavior.

@private
@returns {boolean} boolean indicating whether `process.umask` exhibits expected behavior