Limit/Span (Min,Max) Pair.
TODO: Simultaneous min and max (minmax) can be optimized to 3/4 comparison. TODO: Decide on either Span, MinMax or Limits
Expand Limits to include a.
https://stackoverflow.com/questions/21241878/generic-span-type-in-phobos
See Implementation
Limit/Span (Min,Max) Pair.
TODO: Simultaneous min and max (minmax) can be optimized to 3/4 comparison. TODO: Decide on either Span, MinMax or Limits