# File lib/net/ftp.rb, line 418
    def retrlines(cmd) # :yield: line
      synchronize do
        voidcmd("TYPE A")
        conn = transfercmd(cmd)
        loop do
          line = conn.gets
          break if line == nil
          if line[-2, 2] == CRLF
            line = line[0 .. -3]
          elsif line[-1] == ?\n
            line = line[0 .. -2]
          end
          yield(line)
        end
        conn.close
        voidresp
      end
    end