Returns a new step function where self has been masked by other.
Note when other is as Stairs instance, is is considered equivalent to its boolean value, that is, the result of
Stairs.make_boolean(). As a result any part of the domain where other is zero-valued, or not defined, will be undefined in the resulting step function.
Also note that
.mask((a,b))is equivalent to
.mask(sc.Stairs().layer(a,b))but defers to a faster implementation.
Stairs, or tuple
If other is a tuple (a,b) then it is assumed that a < b and that a and b both belong to the domain of the step function represented by self