If exactly two trains in total are shown, with all trains pointing rightward.
return trains  ;return number of  #1 ;return #1 that are pointing rightward ;return number of  #3 ;return if  #2 is equal to  two ;return if  #4 is equal to  #2 ;return if  both  #5 and #6 are true
['select', 'aggregate', 'filter', 'aggregate', 'boolean', 'boolean', 'boolean']