Add left and right correspondence to bijection such that left and right are unique in their respective sets and only correspond to each other.

Number of bindings. O(n) time.

Check both sides for key membership.

Check for membership of correspondence using left key.

Check for membership of correspondence using right key.

• raises Not_found

  if left is not found.

• raises Not_found

  if right is not found.

Remove the left, right binding if it exists. Return the same bijection otherwise.

Remove the binding with left key if it exists. Return the same bijection otherwise.

Remove the binding with right key if it exists. Return the same bijection otherwise.

Return the bindings as a list of (left, right) values.

Return the bindings as a list of (right, left) values.