code: function getThemeMapByFile(file) {
  	if ( fileSet.has(file) ) {
  		let ary = [...fileSet].push(file);
  		throw Err.cat(MODULE, ary, new Err('theme circular extend'));
  	}
  	fileSet.add(file);
  
  	btf = new Btf(file);
  	let superPkg = (btf.getText('extend') || '').trim();					// 继承的模块名
  	let superTheme;
  	let theme = btf.getMap('theme');
  
  	if ( superPkg ) {
  		superTheme = getThemeMapByFile( getThemeBtfFileByPkg(superPkg) );
  		theme.forEach((v,k)=>superTheme.set(k,v));							// 覆盖父类风格
  		theme = superTheme;
  	}
  	return theme;
  }
docs: 循环继承检查用