code: public boolean isPrefixOf(MatcherPath that) {
          checkArgNotNull(that, "that");
          return element.level <= that.element.level &&
                  (this == that || (that.parent != null && isPrefixOf(that.parent)));
      }
docs: Determines whether this path is a prefix of the given other path.
  
  @param that the other path
  @return true if this path is a prefix of the given other path