using_each_crlf_line

# File lib/net/protocol.rb, line 286
    def using_each_crlf_line
      @wbuf = ''
      yield
      if not @wbuf.empty?   # unterminated last line
        write0 @wbuf.chomp + "\r\n"
      elsif @written_bytes == 0   # empty src
        write0 "\r\n"
      end
      write0 ".\r\n"
      @wbuf = nil
    end