copy method

(A, B, C, D, E, F, G, H, I, J, K, L, M) copy({
  1. A? $1,
  2. B? $2,
  3. C? $3,
  4. D? $4,
  5. E? $5,
  6. F? $6,
  7. G? $7,
  8. H? $8,
  9. I? $9,
  10. J? $10,
  11. K? $11,
  12. L? $12,
  13. M? $13,
})

Implementation

(A, B, C, D, E, F, G, H, I, J, K, L, M) copy({
  A? $1,
  B? $2,
  C? $3,
  D? $4,
  E? $5,
  F? $6,
  G? $7,
  H? $8,
  I? $9,
  J? $10,
  K? $11,
  L? $12,
  M? $13,
}) =>
    (
      $1 ?? this.$1,
      $2 ?? this.$2,
      $3 ?? this.$3,
      $4 ?? this.$4,
      $5 ?? this.$5,
      $6 ?? this.$6,
      $7 ?? this.$7,
      $8 ?? this.$8,
      $9 ?? this.$9,
      $10 ?? this.$10,
      $11 ?? this.$11,
      $12 ?? this.$12,
      $13 ?? this.$13
    );