fatorial.py

def f(a, b, c, d):
  print(a, b, c, d)
  if a == 0:
    return b + c
  elif a == 1:
    if c == 0:
      return 0
    else:
      return f(0, f(1, b, c - 1, d + 1), b, d + 1)
  elif a == 2:
    if c == 0:
      return 1
    else:
      return f(1, f(0, c - 1, 1, d + 1), f(2, b, c - 1, d + 1), d + 1)
      
if __name__ == "__main__":
  print(f(2, 7, 7, 0))