S=true 1 undefined
T=true 2 undefined
S=true 10 1
T=true 11 2
S=false 10 10
T=false undefined 11
S=false 10 10
T=false undefined undefined
S=false 10 10
T=false undefined undefined
S=true 20 10
T=false undefined undefined
S=true 30 20
T=true 31 undefined
S=false 30 30
T=false undefined 31
S=false 30 30
T=false undefined undefined