Returns an interval that has been expanded on each side by the given
distance "margin". If "margin" is negative, then shrink the interval on
each side by "margin" instead. The resulting interval may be empty. Any
expansion of an empty interval remains empty.
Returns an interval that has been expanded on each side by the given distance "margin". If "margin" is negative, then shrink the interval on each side by "margin" instead. The resulting interval may be empty. Any expansion of an empty interval remains empty.