docs: function cleanDir( path, _preserveGit ) {
      const
      preserveGit = typeof _preserveGit !== 'undefined' ? _preserveGit : false,
      fullPath = Path.resolve( path );
      // If the pah does not exist, everything is fine!
      if ( !FS.existsSync( fullPath ) ) return;
  
      if ( preserveGit ) {
  
          /*
           * We must delete the content of this folder but preserve `.git`.
           * The `www` dir, for instance, can be used as a `gh-pages` branch.
           */
          const files = FS.readdirSync( path );
          files.forEach( function forEachFile( filename ) {
              if ( filename === '.git' ) return;
              const
              filepath = Path.join( path, filename ),
              stat = FS.statSync( filepath );
              if ( stat.isDirectory() ) {
                  if ( filepath !== '.' && filepath !== '..' ) PathUtils.rmdir( filepath );
              } else FS.unlinkSync( filepath );
          } );
      } else {
          // Brutal clean: remove dir and recreate it.
          PathUtils.rmdir( path );
          PathUtils.mkdir( path );
      }
  }