Previously, `make_date`, `make_timestamp`, and `make_timestamptz` built-ins were not implemented. In addition, a new signature for `date_trunc` was not implemented. This was inadequate because it ...

def date_trunc_sql (self, lookup_type, field_name, tzname=None) Since there already exists code to incude the time zone this could be fixed by updating the function definition and adding an if ...