convert python to python3 code example

Example 1: python2 to python3 converter

# example.py file 
def greet(name):
    print "Hello, {0}!".format(name)
print "What's your name?"
name = raw_input()
greet(name)

##It can be converted to Python 3.x code via 2to3 on the command line:
# 2to3 example.py

Example 2: python3 to python

alias python=python3