def lookup_single path
    objs = lookup path
    Util.err "Not found: #{path.inspect}" if objs.empty?
    Util.err "More than one match for #{path.inspect}" if objs.size > 1
    objs.first
  end
def lookup_single path
    objs = lookup path
    Util.err "Not found: #{path.inspect}" if objs.empty?
    Util.err "More than one match for #{path.inspect}" if objs.size > 1
    objs.first
  end
Utility methods