(self, x)
Returns true if argument exists at given index.
           Accepts: integer.
Returns true if argument exists at given index.
           Accepts: integer.
Returns true if argument exists at given index . Accepts : integer .
def has(self, x):
        """Returns true if argument exists at given index.
           Accepts: integer.
        """

        try:
            self.all[x]
            return True
        except IndexError:
            return False
def has ( self , x ) : try : self . all [ x ] return True except IndexError : return False