equals function
check if the string matches the comparison
Implementation
bool equals(String str, Object? comparison) {
if (comparison == null) {
// Explicitly check if `comparison` is null because calling `toString`
// on `null` will return 'null'. This is an issue when comparing to
// the string 'null'. Also, `str` will never be null so if `comparison`
// is null we can simply return false.
return false;
}
return str == comparison.toString();
}