def latest(self, conn=None):
"""
Returns most recent SurveyData point available.
"""
if not conn:
conn = self.conn
sql = "select * from %s where survey_id = %s ORDER BY created_at DESC LIMIT 1"
rows = conn.execute(sql % (SurveyData.table_name(), self.id))
row = rows.fetchone()
if row:
return SurveyData.load(conn, row)
