docs: def connect(self, port=None):
          ''' Open a serial connection to the arm. '''
          if port is None:
              self.port = search_for_port('/dev/ttyUSB*', 'ROBOFORTH\r\n',
                                          'ROBOFORTH')
          else:
              self.port = port
  
          if self.port is None:
              raise ArmException('ST Robotics connection not found.')
  
          self.ser = r12_serial_port(port)
  
          if not self.ser.isOpen():
              self.ser.open()
  
          if not self.ser.isOpen():
              raise ArmException('Failed to open serial port. Exiting.')
  
          return self.port