def rassoc(obj)
      obj = Erlang.from(obj)
      each { |entry| return Erlang::Tuple[*entry] if obj == entry[1] }
      return nil
    end
def rassoc(obj)
      obj = Erlang.from(obj)
      each { |entry| return Erlang::Tuple[*entry] if obj == entry[1] }
      return nil
    end
Searches through the `Map`, comparing `obj` with each value (using `#==`).
 When a matching value is found, return the `[key, value]` pair as a `Tuple`.
 Return `nil` if no match is found.

 @example
   Erlang::Map["A" => 1, "B" => 2, "C" => 3].rassoc(2)  # => Erlang::Tuple["B", 2]

 @param obj [Object] The value to search for (using #==)
 @return [Tuple]