cutFirst method
cut using first instance of separator,
returning the before and after parts
found is true if separator was found
Implementation
(String before, String after, bool found) cutFirst(String separator) {
if (isEmpty || separator.isEmpty) {
return (this, '', false);
}
var rng = characters.findFirst(separator.characters);
if (rng == null) {
return (this, '', false);
}
var before = rng.charactersBefore.toString();
var after = rng.charactersAfter.toString();
return (before, after, true);
}