input: Write a function to generate Fibonacci numbers using a recursive approach. The function should take an integer `n` and return the nth Fibonacci number. The first two Fibonacci numbers are both 1.
  assert fibonacci(1)==1
  assert fibonacci(2)==1
  assert fibonacci(10)==55
  assert fibonacci(1)==1
  assert fibonacci(2)==1
  assert fibonacci(10)==55
output: def fibonacci(n):
      if n == 1 or n == 2:
          return 1
      return fibonacci(n-1) + fibonacci(n-2)