anchor.diff:              case 67:
               case 69:
               case 95:
  -              // TODO(vtl): FIXME soon.
  -assert(false);
  +              assert(!assertFailOnUnimplemented);
                 break;
               case 1001:
               case 1002:
  
positive.code:             case 12:
              case 20:
                // TODO(vtl): FIXME soon.
  assert(false);
                break;
  default:
  // TODO(vtl): FIXME soon.
  assert(false);
  break;
            }
          } else if (_csiC1 == 63) {  // C1 = '?'.
            switch (_csiParams[0]) {
  
negative.code:         break;
        case 98:  // 'b': Repeat the preceding graphic character.
          // TODO(vtl): FIXME soon.
          assert(!assertFailOnUnimplemented);
          break;
        case 99:  // 'c': Send device attributes.
          // TODO(vtl): FIXME soon.
          assert(!assertFailOnUnimplemented);
          break;
        case 100:  // 'd': Line position absolute.
          if (_csiC1 != 0) {  // Only accept no C1.
  