Performs operation op on term

First argument is original term. Second is operation, that get matched against functions in implementations. Third is a tuple, where first item should be result of the operation, and second is anything else.

Function should return tuple with :ok atom and tuple {result, anything}

Returns the opposite of operation

If operation is not revertable, should return {:error, reason}

Examples

iex> Differ.diffable.revert("", {:del, "ttypo"})
{:ok, {:ins, "ttypo"}}

iex> Differ.diffable.revert("", {:remove, 10})
{:error, "Operation is not revertable"}