input: Write a function to describe the concept of recursion in Python. The function should explain that recursion is a powerful technique for solving problems by defining a problem in terms of itself, breaking it down into smaller problems, and combining the results until the original problem is solved. A recursive function in Python is one that calls itself.
  assert describe_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."
output: def describe_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."