Generic get() for one item only

        >>> ec2.instances.get(name='production-web-01')
        <Instance: ...>

def get(cls, **kwargs):
        """
        Generic get() for one item only

        >>> ec2.instances.get(name='production-web-01')
        <Instance: ...>
        """
        things = cls.filter(**kwargs)
        if len(things) > 1:
            # Raise an exception if more than one object is matched
            raise cls.MultipleObjectsReturned
        elif len(things) == 0:
            # Rase an exception if no objects were matched
            raise cls.DoesNotExist
        return things[0]