comefrom: <doocs>0921.Minimum Add to Make Parentheses Valid_1.py
code: def minAddToMakeValid( s: str) -> int:
      stk = []
      for c in s:
          if c == '(':
              stk.append(c)
          else:
              if stk and stk[-1] == '(':
                  stk.pop()
              else:
                  stk.append(c)
      return len(stk)
masked: def sample_funcname ( var_0 : str ) -> int :
      var_3 = [ ]
      for var_4 in var_0 :
          if var_4 == '(' :
              var_3.append ( var_4 )
          else :
              if var_3 and var_3 [ - 1 ] == '(' :
                  var_3.pop ( )
              else :
                  var_3.append ( var_4 )
      return len ( var_3 )
  