input: Write a function to solve a given problem in Python using recursion. The function should demonstrate a problem that can be broken down into smaller instances of itself, and ultimately solved by combining results from these smaller instances. Ensure the recursive function calls itself in a manner that reduces the problem size until a base case is met.
  assert solve_recursion_problem([2, 4, 8, 0, 3, 9])==1
output: def solve_recursion_problem(arr):
      if len(arr) == 1:
          return arr[0]
      else:
          return arr[0] + solve_recursion_problem(arr[1:])