def export_date_time(format):
 def export_date_time_lambda(value):
  if (not value):
   return ''
  return datetime.datetime.strftime(value, format)
 return export_date_time_lambda

def export_date_time ( format ) : def export_date_time_lambda ( value ) : if ( not value ) : return '' return datetime . datetime . strftime ( value , format ) return export_date_time_lambda
a wrapper around strftime .