rem: return;
add: { _error->Warning(_("Unable to load debtags vocabulary, perhaps debtags is not installed?"));  return; }
context: static void init_vocabulary(){  if(facet_descriptions != NULL)    {      assert(tag_descriptions != NULL);      return;    }  facet_descriptions = new facet_description_map;  tag_descriptions = new tag_description_map;  FileFd F(aptcfg->FindFile("DebTags::Vocabulary", "/usr/share/debtags/vocabulary"),	   FileFd::ReadOnly);  if(!F.IsOpen())    // Fail silently; debtags need not be installed.    return;  pkgTagFile tagfile(&F);  pkgTagSection sec;  while(tagfile.Step(sec))    {      string facet;      const char *start, *end;      if(sec.Find("Facet", start, end))	{	  facet.assign(start, end-start);	  if(sec.Find("Description", start, end))	    (*facet_descriptions)[facet] = string(start, end-start);	}      else if(sec.Find("Tag", start, end))	{	  string tag(start, end-start);	  if(sec.Find("Description", start, end))	    (*tag_descriptions)[tag] = string(start, end-start);	}    }}