input: Write a function to provide an explanation of how recursion works in Python and how it can be used to solve problems. The function should explain that recursion involves defining a problem in terms of itself, breaking it down into smaller problems, and combining results from these smaller problems to solve the original problem. The function should also indicate that in Python, a recursive function is one that calls itself.
  assert explain_recursion()== "Recursion is a powerful technique for solving problems. It involves defining a problem in terms of itself. A recursion problem is solved by breaking it down into smaller problems, until the problem is small enough to be solved directly. The result from a smaller problem can then be combined with the result from the larger problem, until the original problem is solved. In Python, a recursive function is one that calls itself."
  assert explain_recursion() is not None
  assert len(explain_recursion()) > 0
output: def explain_recursion():
      return "Recursion is a powerful technique for solving problems. It involves defining a problem in terms of itself. A recursion problem is solved by breaking it down into smaller problems, until the problem is small enough to be solved directly. The result from a smaller problem can then be combined with the result from the larger problem, until the original problem is solved. In Python, a recursive function is one that calls itself."