function expandAcronyms( str ) {
	var tokens;
	var token;
	var out;
	var key;
	var i;
	var j;

	if ( !isString( str ) ) {
		throw new TypeError( format( 'invalid argument. Must provide a string. Value: `%s`.', str ) );
	}
	out = '';
	tokens = tokenize( str, true );
	for ( i = 0; i < tokens.length; i++ ) {
		token = tokens[ i ];
		if ( isUppercase( token ) ) {
			for ( j = 0; j < KEYS.length; j++ ) {
				key = KEYS[ j ];
				if ( lowercase( token ) === key ) {
					token = ACRONYMS[ key ];
					break;
				}
			}
		} else {
			for ( j = 0; j < KEYS.length; j++ ) {
				key = KEYS[ j ];
				if ( token === key ) {
					token = ACRONYMS[ key ];
					break;
				}
			}
		}
		out += token;
	}
	return out;
}
Expands acronyms in a string.

@param {string} str - string to convert
@throws {TypeError} must provide a string
@returns {string} string with expanded acronyms

@example
var str = 'LOL, this is fun. I am ROFL.';
var out = expandAcronyms( str );
// returns 'laughing out loud, this is fun. I am rolling on the floor laughing.'

@example
var str = 'brb, I need to check my mail. thx!';
var out = expandAcronyms( str );
// returns 'be right back, I need to check my mail. thanks!'