5

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Write a function called that takes a string of parentheses, and determines if the order of the parentheses is valid.
The function should return true if the string is valid, and false if it's invalid.

Examples
"()"              =>  true
")(()))"          =>  false
"("               =>  false
"(())((()())())"  =>  true
Constraints
0 <= input.length <= 100

Along with opening (() and closing ()) parenthesis, input may contain any valid ASCII characters.
Furthermore, the input string may be empty and/or not contain any parentheses at all. Do not treat other forms of brackets as parentheses (e.g. [], {}, <>).




def valid_parentheses(string):
  return #TODO



#tests
Test.assert_equals(valid_parentheses("  ("),False)
Test.assert_equals(valid_parentheses(")test"),False)
Test.assert_equals(valid_parentheses(""),True)
Test.assert_equals(valid_parentheses("hi())("),False)
Test.assert_equals(valid_parentheses("hi(hi)()"),True)



















































































#one_solution
def valid_parentheses(string):
    abertos = 0
    for s in string:
        if s == '(':
            abertos += 1
        elif s == ')':
            abertos -= 1
            if abertos < 0:
                break
    return True if abertos == 0 else False