'Adds a score to the gravityScore Attribute we put on divs
we\'ll get the current score then add the score we\'re passing
in to the current.'

def update_score(self, node, add_to_score):

    current_score = 0
    score_string = self.parser.getAttribute(node, 'gravityScore')
    if score_string:
        current_score = float(score_string)
    new_score = (current_score + add_to_score)
    self.parser.setAttribute(node, 'gravityScore', str(new_score))
