detect_spaces_at_bol (Erubis::Converter)

    # File lib/erubis/converter.rb, line 47
        def detect_spaces_at_bol(text, is_bol)
          lspace = nil
          if text.empty?
            lspace = "" if is_bol
          elsif text[-1] == ?\n
            lspace = ""
          else
            rindex = text.rindex(?\n)
            if rindex
              s = text[rindex+1..-1]
              if s =~ /\A[ \t]*\z/
                lspace = s
                #text = text[0..rindex]
                text[rindex+1..-1] = ''
              end
            else
              if is_bol && text =~ /\A[ \t]*\z/
                #lspace = text
                #text = nil
                lspace = text.dup
                text[0..-1] = ''
              end
            end
          end
          return lspace
        end