'Consumes a } or ) character.
Returns the number of charactes consumed. (Does not update
self.offset)'

def parse_closer(self):

    assert (self.formula[self.offset] in (')', '}'))
    token = self.token_stack.pop().get_closer()
    if (token.value != self.formula[self.offset]):
        raise TokenizerError(("Mismatched    (    and    {    pair    in    '%s'" % self.formula))
    self.items.append(token)
    return 1
