anchor.diff:    }
   
     static Uid parse(String s) {
  -    if (_validator(s) == null) return null;
  +    if (validate(s) == null) return null;
       if (checkWellKnown) {
         Uid wellKnownUid = wellKnownUids[s];
         if (wellKnownUid != null) return wellKnownUid;
       }
       return new Uid.constant(s);
     }
  -
  -  static String _validator(String s) => validateString(s, kMin, kMax, kPred);
   
     static String get random => Uuid.randomUid;
   
  
positive.code:     return root;
    }
  
    static bool isValid(Uid uid) => (validate(uid) == null) ? false : true;
  
    static Uid validate(Uid uid) => (_validator(uid._value) == null) ? null : uid;
  
    static final RegExp uidPattern = new RegExp(r"[012]((\.0)|(\.[1-9]\d*))+");
  
  
negative.code:   ///
    /// Note: Random [Uid]s have a root of "2.25" as defined by the OID
    /// Standard (see http://www.oid-info.com/get/2.25).
    Uid([String s]) : _value = (s == null) ? Uuid.randomUid : validate(s);
  
    /// Creates a constant [Uid].  Used to create 'Well Known' DICOM [Uid]s.
    const Uid.constant(this._value);
  