A class for partially ordered data.
Result of comparing this with operand that.
this
that
Result of comparing this with operand that. Returns None if operands are not comparable. If operands are comparable, returns Some(x) where - x < 0 iff this < that - x == 0 iff this == that - x > 0 iff this > that
None
Some(x)
x < 0
this < that
x == 0
this == that
x > 0
this > that