'Sets a hint for how this query should run.
The query hint gives us information about how best to execute your query.
Currently, we can only do one index scan, so the query hint should be used
to indicates which index we should scan against.
Use FILTER_FIRST if your first filter will only match a few results. In
this case, it will be most efficient to scan against the index for this
property, load the results into memory, and apply the remaining filters
and sort orders there.
Similarly, use ANCESTOR_FIRST if the query\'s ancestor only has a few
descendants. In this case, it will be most efficient to scan all entities
below the ancestor and load them into memory first.
Use ORDER_FIRST if the query has a sort order and the result set is large
or you only plan to fetch the first few results. In that case, we
shouldn\'t try to load all of the results into memory; instead, we should
scan the index for this property, which is in sorted order.
Note that hints are currently ignored in the v3 datastore!
Arg:
one of datastore.Query.[ORDER_FIRST, ANCESTOR_FIRST, FILTER_FIRST]
Returns:
# this query
Query'

def Hint(self, hint):

    if (hint is not self.__query_options.hint):
        self.__query_options = datastore_query.QueryOptions(hint=hint, config=self.__query_options)
    return self
