input: Write a function to implement the Fibonacci sequence where the function takes an integer \( n \) as input and returns the nth Fibonacci number. The Fibonacci sequence is defined as: F(0) = 0, F(1) = 1, and F(n) = F(n-1) + F(n-2) for n > 1.
  
  def fibonacci_seq(n): 
      if n==0: 
          return 0
      elif n==1: 
          return 1
      else: 
          return fibonacci_seq(n-1)+fibonacci_seq(n-2)
          
  assert fibonacci_seq(0)==0
  assert fibonacci_seq(1)==1
  assert fibonacci_seq(2)==1
  assert fibonacci_seq(5)==5
  assert fibonacci_seq(10)==55
output: def fibonacci_seq(n): 
      if n==0: 
          return 0
      elif n==1: 
          return 1
      else: 
          return fibonacci_seq(n-1)+fibonacci_seq(n-2)