all_ method
Returns true if all elements satisfy predicate. Vacuously
true for an empty source.
Short-circuits at the first non-match.
Implementation
bool all_(Expr predicate) {
final lambda = _requirePredicate('all_', predicate);
final paramName = lambda.params.first.name;
final body = lambda.body;
for (final e in this) {
if (body.eval({paramName: e}) != true) return false;
}
return true;
}