message: Document the choice of i32 for table_id
diff: @@ -108,6 +108,10 @@ impl<F: Field> SingleLookup<F> {
  /// A spec for checking that the given vector belongs to a vector-valued lookup table.
  #[derive(Clone, Serialize, Deserialize)]
  pub struct JointLookup<F> {
  + /// The ID for the table associated with this lookup.
  + /// Positive IDs are intended to be used for the fixed tables associated with individual gates,
  + /// with negative IDs reserved for gates defined by the particular constraint system to avoid
  + /// accidental collisions.
  pub table_id: i32,
  pub entry: Vec<SingleLookup<F>>,
  }
  