# File lib/librarian/logger.rb, line 21
    def debug(string = nil, &block)
      return unless ui

      if ui.respond_to?(:debug_line_numbers) && ui.debug_line_numbers
        loc = caller.find{|l| !(l =~ /in `debug'$/)}
        if loc =~ /^(.+):(\d+):in `(.+)'$/
          loc = "#{Pathname.new($1).relative_path_from(LIBRARIAN_PATH)}:#{$2}:in `#{$3}'"
        end
        ui.debug { "[Librarian] #{string || yield} [#{loc}]" }
      else
        ui.debug { "[Librarian] #{string || yield}" }
      end
    end