input: Write a function to generate the nth Fibonacci number using a recursive approach. The function should return the Fibonacci number at the nth position. If n is 1 or 2, the function should return 1. For other values of n, the function should recursively return the sum of the two preceding Fibonacci numbers.
  
  assert fibonacci(1)==1
  assert fibonacci(2)==1
  assert fibonacci(3)==2
  assert fibonacci(4)==3
  assert fibonacci(5)==5
output: def fibonacci(n):
      if n == 1 or n == 2:
          return 1
      else:
          return fibonacci(n-1) + fibonacci(n-2)