If there are only two dogs pulling one of the sleds.
return dogs ;return sleds ;return #1 that are  pulling #2 ;return number of #3 for each #2 ;return #2 where #4 is  equal to two ;return number of #5 ;return If #5 is  equal to one
['select', 'select', 'filter', 'group', 'comparative', 'aggregate', 'boolean']