What are the first names and country codes for players who won both the WTA Championships and the Australian Open?
return players ;return #1 who  won WTA Championships ;return #1 who  won Australian Open ;return #1 in both #2 and  #3 ;return first names of  #4 ;return country codes for #4 ;return #5 ,  #6
['select', 'filter', 'filter', 'intersection', 'project', 'project', 'union']