Question: A common task in an editor application, such as WordPad or TextEdit, is parentheses matching. For example, "(()())" is a valid string of parentheses, because each opening bracket has a corresponding closing bracket. On the other hand, "(()" is not a valid string. Another invalid example would be ")(," as the opening bracket should precede the closing bracket. Write a recursive function that takes a string as input and returns True if the string is valid with respect to matched parentheses. To simplify matters, begin by considering that the input string has only "(" or ")" and no other characters.