anchor.diff:  // Author: tomyeh
   library entity.oid;
   
  -import "dart:math" show Random, min;
  +import "dart:math" show Random, min, max;
   
   //Note: we use characters a-z, A-Z, 0-9 and _, s.t., the user  can select all
   //by double-clicking it (they also valid characters no need of escapes).
  
positive.code:     }
    }
  
    _prefix = bytes[OID_LENGTH - 1] & 0x1f;
    _prefixEnd = min((bytes[OID_LENGTH] & 0x1f) + _prefix + 5,
        _CC_RANGE - 1);
  
    bytes.removeRange(OID_LENGTH - 1, _CHAR_PER_INT * _INT_LEN);
    for (int i = OID_LENGTH - 1; --i >= 0;)
  
negative.code: //OID is 24 chars (23 random number + 1 random sequential number) > 63^23 = 2.4e41
  //so it is about 10K more than 128 bit UUID (where 122 is effective: 5.3e36)
  //(note: Git revision is 2^40 about 1.46e48)
  //(note: the sequential number is about 12 per seed, i.e., 63/12 ~ 5)
  
  /** The type of random generator
   *
  