(yellow,blue):  yellow
(green,undef):  green
(undef,teal):   teal
(undef,chartreuse):     default
(undef,undef):  default
(undef,undef):  5
(4,undef):      4
(444,undef):    444
(undef,3):      3
(undef,333):    5
(6,7):  6