module Redis::Commands::Lists

def _normalize_move_wheres(where_source, where_destination)
  where_source      = where_source.to_s.upcase
  where_destination = where_destination.to_s.upcase
  if where_source != "LEFT" && where_source != "RIGHT"
    raise ArgumentError, "where_source must be 'LEFT' or 'RIGHT'"
  end
  if where_destination != "LEFT" && where_destination != "RIGHT"
    raise ArgumentError, "where_destination must be 'LEFT' or 'RIGHT'"
  end
  [where_source, where_destination]
end