def open(io)
      begin
        @@logger = Logger.new(io)
      rescue => e
        @@logger = Logger.new($stderr)
        Log.fatal "Cannot open log file: #{e.message}"
      end
    end
def open(io)
      begin
        @@logger = Logger.new(io)
      rescue => e
        @@logger = Logger.new($stderr)
        Log.fatal "Cannot open log file: #{e.message}"
      end
    end
Redirect all log messages to the given IO.
 @param io [IO] Output file descriptor