from functools import wraps
def recfun(f):
    @wraps(f)
    def _f(*a,**kwa): return f(_f,*a,**kwa)
    return _f
@recfun
# it's a decorator,so a separate class+method don't need to be defined
# for each function and the class does not need to be instantiated,# as with Alex Hall's answer
def fact(self,n):
    if n > 0:
        return n * self(n-1)  # doesn't need to be self(self,n-1),# as with lkraider's answer
    else:
        return 1
print(fact(10))  # works,as opposed to dursk's answer