Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "lcddriver.py", line 57, in __init__
   self.lcd_write(0x03)
 File "lcddriver.py", line 82, in lcd_write
   self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))
 File "lcddriver.py", line 76, in lcd_write_four_bits
   self.lcd_device.write_cmd(data | LCD_BACKLIGHT)
 File "i2c_lib.py", line 11, in write_cmd
   self.bus.write_byte(self.addr, cmd)
IOError: [Errno 5] Input/output error