'Sets the column(s) to be used for ordering
Default order is ascending, prepend a \'-\' to any column name for descending
*Note: column names must be a clustering key*
.. code-block:: python
from uuid import uuid1,uuid4
class Comment(Model):
photo_id = UUID(primary_key=True)
comment_id = TimeUUID(primary_key=True, default=uuid1) # second primary key component is a clustering key
comment = Text()
sync_table(Comment)
u = uuid4()
for x in range(5):
Comment.create(photo_id=u, comment="test %d" % x)
print("Normal")
for comment in Comment.objects(photo_id=u):
print comment.comment_id
print("Reversed")
for comment in Comment.objects(photo_id=u).order_by("-comment_id"):
print comment.comment_id'

def order_by(self, *colnames):

    if (len(colnames) == 0):
        clone = copy.deepcopy(self)
        clone._order = []
        return clone
    conditions = []
    for colname in colnames:
        conditions.append('"{0}"    {1}'.format(*self._get_ordering_condition(colname)))
    clone = copy.deepcopy(self)
    clone._order.extend(conditions)
    return clone
