overload.py

registry = {}
class MultiMethod(object):
    def __init__(self, name):
        self.name = name
        self.typemap = {}
    def __call__(self, *args):
        types = tuple(arg.__class__ for arg in args)
        function = self.typemap.get(types)
        if function is None:
            raise TypeError("no match")
        return function(*args)
    def register(self, types, function):
        self.typemap[types] = function
def overload(*types):
    def register(function):
        name = function.__name__
        mm = registry.get(name)
        if mm is None:
            mm = registry[name] = MultiMethod(name)
        mm.register(types, function)
        return mm
    return register

@overload(int, int)
def area(length, breadth):
    calc = length * breadth
    print (calc)
    
@overload(int)
def area(size):
    calc =  size * size
    print (calc)
@overload(int,int,int)
def area(adj,opp,hyp):
    calc =  adj * opp*hyp
    print (calc)
    
area(3) # returns 9
area(4,5) # returns 20
area(4,5,6) # returns 20