'Returns a "dict" with mappings between ids, desired values, and ids.'

def _calculate_data(self):

    def data(cond, required_value, child):
        'Calculates    data    for    single    item.'
        return (self.add_prefix(cond), str(required_value), self.add_prefix(child))
    return [data(*x) for x in self.dependencies]
