input: Write a function to generate Fibonacci numbers using a recursive approach in Python. The function should take an integer `n` as input and return the nth Fibonacci number. If `n` is 1 or 2, the function should return 1. For other values of `n`, the function should recursively call itself to calculate the sum of the two preceding Fibonacci numbers.
  def fibonacci(n):
      if n == 1 or n == 2:
          return 1
      else:
          return fibonacci(n - 1) + fibonacci(n - 2)
  
  assert fibonacci(1) == 1
  assert fibonacci(2) == 1
  assert fibonacci(10) == 55
  assert fibonacci(15) == 610
  assert fibonacci(1) == 1
output: def fibonacci(n):
      if n == 1 or n == 2:
          return 1
      else:
          return fibonacci(n - 1) + fibonacci(n - 2)