input: Write a function to calculate the Fibonacci number at a given position. If the given position is 0, return 0. If the given position is 1, return 1. For any other position, return the sum of the Fibonacci numbers at the two preceding positions.
  def fibonacci(n):
      if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci(n-1) + fibonacci(n-2)
  
  n = 10
  print(fibonacci(n))
output: def fibonacci(n):
      if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci(n-1) + fibonacci(n-2)