class Relay():	
    global bus
    def __init__(self):
	self.DEVICE_ADDRESS = 0x20      #7 bit address (will be left shifted to add the read write bit)
	self.DEVICE_REG_MODE1 = 0x06
	self.DEVICE_REG_DATA = 0xff
	bus.write_byte_data(self.DEVICE_ADDRESS, self.DEVICE_REG_MODE1, self.DEVICE_REG_DATA)
             
    def ON_1(self):
	    print 'ON_1...'
	    self.DEVICE_REG_DATA &= ~(0x1<<0)  
	    bus.write_byte_data(self.DEVICE_ADDRESS, self.DEVICE_REG_MODE1, self.DEVICE_REG_DATA)

##</code><code>##

#!/usr/bin/perl
use strict;
use Device::SMBus;
use Data::Dumper;
my $dev = Device::SMBus->new(
  I2CBusDevicePath => '/dev/i2c-1',
  I2CDeviceAddress => 0x20,
);
$dev->writeByteData(0x06,0x1<<0);
print Dumper $dev