function isLowercase( value ) {
	return (
		isString( value ) &&
		value === lowercase( value ) &&
		value !== uppercase( value )
	);
}
Tests if a value is a lowercase string.

@param {*} value - value to test
@returns {boolean} boolean indicating whether value is a lowercase string

@example
var bool = isLowercase( 'salt and light' );
// returns true

@example
var bool = isLowercase( 'HELLO' );
// returns false

@example
var bool = isLowercase( 'World' );
// returns false

@example
var bool = isLowercase( '!' );
// returns false