x=int,y=int,z=int
x=int,y=empty,z=empty
x=empty,y=int,z=empty
x=empty,y=empty,z=empty
a=1,y=int,z=int,x=absent
a=1,y=empty,x=absent,z=absent
a=,y=int,z=int,x=absent
a=,y=empty,x=absent,z=absent
x=int,b=2,z=int,y=absent
x=int,b=,z=int,y=absent
x=empty,b=2,y=absent,z=absent
x=empty,b=,y=absent,z=absent
