code: public boolean then(final Interval<C> that) {
          checkNotNull(this.range, that.range);
          return this.intersect(that).equals(this);
      }
docs: Test if an interval implies another.
  @param that interval
  @return true if all elements of this are also in that
  @see #intersect(org.nmdp.ngs.fca.Interval)
  @see <a href="https://en.wikipedia.org/wiki/Allen%27s_interval_algebra">
  Allen's interval algebra</a>