subs method
Implementation
Basic subs(Object substitutions, [bool simultaneous = false]) {
throw UnimplementedError();
// TODO: implement
// if(substitutions is (Object, Object)) {
// return this;
// }
// if(substitutions is Map) {
// return this;
// }
// if(substitutions is List) {
// return this;
// }
//
// return this;
}