'Highlight the entire expression'

def create_tag_expression(self, indices):

    if (self.text.get(indices[1]) in (')', ']', '}')):
        rightindex = (indices[1] + '+1c')
    else:
        rightindex = indices[1]
    self.text.tag_add('paren', indices[0], rightindex)
    self.text.tag_config('paren', self.HILITE_CONFIG)
