docs: def _sendline(self, line):
          """Send exactly one line to the device
  
          Args:
              line str: data send to device
          """
          logging.info('%s: sending line', self.port)
          # clear buffer
          self._lines = []
          try:
              self._read()
          except socket.error:
              logging.debug('%s: Nothing cleared', self.port)
  
          print 'sending [%s]' % line
          self._write(line + '\r\n')
  
          # wait for write to complete
          time.sleep(0.1)