Find the name and revenue of the company that earns the highest revenue in each city.
return cities ;return companies of #1 ;return revenues of #2 ;return #2 where #3 is the  highest for each #1 ;return names of #4 ;return revenues of #4 ;return #5 ,  #6
['select', 'project', 'project', 'group', 'project', 'project', 'union']