explicit_trim_line

# File lib/erb.rb, line 473
      def explicit_trim_line(line)
        line.scan(@scan_reg) do |tokens|
          tokens.each do |token|
            next if token.empty?
            if @stag.nil? && /[ \t]*<%-/ =~ token
              yield('<%')
            elsif @stag && (token == "-%>\n" || token == "-%>\r\n")
              yield('%>')
              yield(:cr)
            elsif @stag && token == '-%>'
              yield('%>')
            else
              yield(token)
            end
          end
        end
      end