input: Write a function to calculate the Fibonacci numbers up to a given number. The function should be named Fibonacci and take one parameter n, where n is the number up to which the Fibonacci sequence should be calculated. If n is 0, the function should return 0. If n is 1, the function should return 1. For any other value of n, the function should return the sum of the two preceding Fibonacci numbers.
  assert Fibonacci(0)==0
  assert Fibonacci(1)==1
  assert Fibonacci(2)==1
  assert Fibonacci(3)==2
  assert Fibonacci(4)==3
output: def Fibonacci(n):
      if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          a, b = 0, 1
          for _ in range(2, n + 1):
              a, b = b, a + b
          return b