input: Write a function to generate Fibonacci numbers recursively. Define the function so that it takes an integer n as input and returns the nth Fibonacci number. The Fibonacci sequence starts with 1 and 1 for the first two numbers, and each subsequent number is the sum of the previous two.
  
  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(5) == 5
  assert fibonacci(10) == 55
  assert fibonacci(15) == 610
output: def fibonacci(n):
      if n == 1 or n == 2:
          return 1
      else:
          return fibonacci(n - 1) + fibonacci(n - 2)