fib_memo_decorator.py

class Memoization(object):
  def __init__(self, func):
    self.func = func
    self.data = {}

  def __call__(self, n, **kwargs):
    if n in self.data:
      return self.data[n]

    self.data[n] = self.func(n)
    return self.data[n]

@Memoization
def fib(n):
  if n <= 1:
    return n

  return fib(n-1) + fib(n-2)

# Decorator
print(fib(50))