input: Write a function to generate Fibonacci numbers using a recursive approach in Python. If the input is 1 or 2, the function should return 1. Otherwise, it should return the sum of the two preceding Fibonacci numbers. 
  assert fibonacci(10)==55
  assert fibonacci(1)==1
  assert fibonacci(2)==1
output: def fibonacci(n):
      if n == 1 or n == 2:
          return 1
      return fibonacci(n-1) + fibonacci(n-2)