code: async function buildDirectDependentTree() {
    const dependents = new Map();
  
    for (const packageName of await _list()) {
      dependents.set(packageName, new Set());
    }
  
    for (const packageName of await _list()) {
      for (const dep of tree.get(packageName)) {
        dependents.get(dep).add(packageName);
      }
    }
  
    return dependents;
  }
docs: Builds a tree of direct dependent packages
  @returns {Map<string, Set>}