Implementation
List<String> get columnSpanPTs => switch(column){
3 => [PT_12, PT_23],
4 => [PT_12, PT_23, PT_34],
5 => [PT_12, PT_23, PT_34, PT_45],
6 => [PT_12, PT_23, PT_34, PT_45, PT_56],
7 => [PT_12, PT_23, PT_34, PT_45, PT_56, PT_67],
_ => [],
};