anchor.diff:  library obj_statements;
   
   import 'package:quiver/collection.dart';
  +import 'package:quiver/core.dart';
   
   part 'src/obj_statements/v_statement.dart';
   part 'src/obj_statements/vt_statement.dart';
  
positive.code:   bool operator ==(other) =>
        identical(other, this) ||
        other is VertexNumPair && other.vNum == vNum && other.vtNum == vtNum;
  }
  
  /// A triple of numbers or which [vNum] is the reference number for a geometric
  
negative.code:           other.vNum == vNum &&
            other.vtNum == vtNum &&
            other.vnNum == vnNum;
  
    int get hashCode => hash3(vNum, vtNum, vnNum);
  }
  
  /// Instance of a 2D curve defined on the parameter range from [start] to [end].
  