input: Write a function to generate Fibonacci numbers up to a given number 'n'. The function should return the n-th Fibonacci number.
  def Fibonacci(n): 
  	if n==0: 
  		return 0
  	if n==1: 
  		return 1
  	else: 
  		return Fibonacci(n-1)+Fibonacci(n-2)
  
  assert Fibonacci(5)==5
  assert Fibonacci(10)==55
  assert Fibonacci(0)==0
  assert Fibonacci(1)==1
  assert Fibonacci(2)==1
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