How to use the @lumino/domutils.Selector.calculateSpecificity function in @lumino/domutils

function itemCmp(a: IItem, b: IItem): number {
    // Sort first based on selector specificity.
    let s1 = Selector.calculateSpecificity(a.selector);
    let s2 = Selector.calculateSpecificity(b.selector);
    if (s1 !== s2) {
      return s2 - s1;
    }

    // If specificities are equal, sort based on rank.
    let r1 = a.rank;
    let r2 = b.rank;
    if (r1 !== r2) {
      return r1 < r2 ? -1 : 1;  // Infinity-safe
    }

    // When all else fails, sort by item id.
    return a.id - b.id;
  }
}

function itemCmp(a: IItem, b: IItem): number {
    // Sort first based on selector specificity.
    let s1 = Selector.calculateSpecificity(a.selector);
    let s2 = Selector.calculateSpecificity(b.selector);
    if (s1 !== s2) {
      return s2 - s1;
    }

    // If specificities are equal, sort based on rank.
    let r1 = a.rank;
    let r2 = b.rank;
    if (r1 !== r2) {
      return r1 < r2 ? -1 : 1;  // Infinity-safe
    }

    // When all else fails, sort by item id.
    return a.id - b.id;
  }
}

if (sqm === SequenceMatch.Partial) {
        if (!partial && targetDistance(binding.selector, event) !== -1) {
          partial = true;
        }
        continue;
      }

      // Ignore the match if the selector doesn't match, or if the
      // matched node is farther away than the current best match.
      let td = targetDistance(binding.selector, event);
      if (td === -1 || td > distance) {
        continue;
      }

      // Get the specificity for the selector.
      let sp = Selector.calculateSpecificity(binding.selector);

      // Update the best match if this match is stronger.
      if (!exact || td < distance || sp >= specificity) {
        exact = binding;
        distance = td;
        specificity = sp;
      }
    }

    // Return the match result.
    return { exact, partial };
  }