docs: def usedby_packages(self, deps_file_path=None, depslock_file_path=None, packages=None):
          """
          Lock packages. Downloader search packages
          """
          if deps_file_path is None:
              deps_file_path = self._deps_path
          if depslock_file_path is None:
              depslock_file_path = self._depslock_path
          if deps_file_path == depslock_file_path:
              depslock_file_path += '.lock'
  
          if packages is None:
              self.search_dependencies(deps_file_path)
          else:
              self._root_package.packages = packages
          self._log.info('Done!')