'Retrieve a value set for a subject\'s attribute.
This method is easy to use but always gets the latest version of the
attribute. It is more flexible and efficient to use the other Resolve
methods.
Args:
subject: The subject URN.
attribute: The attribute.
token: An ACL token.
Returns:
A (value, timestamp in microseconds) stored in the datastore cell, or
(None, 0). Value will be the same type as originally stored with Set().
Raises:
AccessError: if anything goes wrong.'

def Resolve(self, subject, attribute, token=None):

    for (_, value, timestamp) in self.ResolveMulti(subject, [attribute], token=token, timestamp=self.NEWEST_TIMESTAMP):
        return (value, timestamp)
    return (None, 0)
