This function takes a single parameter, s, which is the string of parentheses to check for validity. It initializes an empty stack and an object mapping that maps closing parentheses to their corresponding open parentheses. It then iterates through the string, for each character, if it is an open parenthesis, push it onto the stack. If it is a closing parenthesis, check if the top of the stack is the corresponding open parenthesis. If it is, pop the top element from the stack. If it is not or the stack is empty, the input string is not valid. After iterating through the entire string, if the stack is empty, the input string is valid; otherwise, it is not.