stringInter function
Implementation
stringInter() {
var s = 'string interpolation';
assert('Dart has $s, which is very handy.' ==
'Dart has string interpolation, '
'which is very handy.');
assert('That deserves all caps. ' + '${s.toUpperCase()} is very handy!' ==
'That deserves all caps. '
'STRING INTERPOLATION is very handy!');
}