Overload __radd__ method to handle right side addition

class Commuter: #  w  ww .j  a  v  a2  s .c o  m
    def __init__(self, val): 
        self.val = val 
    def __add__(self, other): 
        print 'add', self.val, other 
    def __radd__(self, other): 
        print 'radd', self.val, other 

x = Commuter(88) 
y = Commuter(99) 

x + 1                           # __add__: instance + noninstance
1 + y                           # __radd__: noninstance + instance
x + y                           # __add__: instance + instance