def check_aggregate_support(self, aggregate):
        if aggregate.sql_function in ('STDDEV_POP', 'VAR_POP'):
            pg_version = self.connection.pg_version
            if pg_version >= 80200 and pg_version <= 80204:
                raise NotImplementedError('PostgreSQL 8.2 to 8.2.4 is known to have a faulty implementation of %s. Please upgrade your version of PostgreSQL.' % aggregate.sql_function)
this method set _givens, _whens and _thens to the class,
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/backends/postgresql_psycopg2/operations.py/DatabaseOperations.check_aggregate_support--crossover with--dataset/ETHPy150Open hltbra/pyhistorian/pyhistorian/steps.py/Step._set_step_attrs