# File lib/sprockets/source_line.rb, line 67
      def interpolate_constants!(result, constants)
        result.gsub!(/<%=(.*?)%>/) do
          constant = $1.strip
          if value = constants[constant]
            value
          else
            raise UndefinedConstantError, "couldn't find constant `#{constant}' in #{inspect}"
          end
        end
      end