# File lib/mail/parsers/rfc2822_obsolete.rb, line 384
    def _nt_obs_FWS
      start_index = index
      if node_cache[:obs_FWS].has_key?(index)
        cached = node_cache[:obs_FWS][index]
        @index = cached.interval.end if cached
        return cached
      end

      i0, s0 = index, []
      s1, i1 = [], index
      loop do
        r2 = _nt_WSP
        if r2
          s1 << r2
        else
          break
        end
      end
      if s1.empty?
        @index = i1
        r1 = nil
      else
        r1 = instantiate_node(SyntaxNode,input, i1...index, s1)
      end
      s0 << r1
      if r1
        s3, i3 = [], index
        loop do
          i4, s4 = index, []
          r5 = _nt_CRLF
          s4 << r5
          if r5
            s6, i6 = [], index
            loop do
              r7 = _nt_WSP
              if r7
                s6 << r7
              else
                break
              end
            end
            if s6.empty?
              @index = i6
              r6 = nil
            else
              r6 = instantiate_node(SyntaxNode,input, i6...index, s6)
            end
            s4 << r6
          end
          if s4.last
            r4 = instantiate_node(SyntaxNode,input, i4...index, s4)
            r4.extend(ObsFWS0)
          else
            @index = i4
            r4 = nil
          end
          if r4
            s3 << r4
          else
            break
          end
        end
        r3 = instantiate_node(SyntaxNode,input, i3...index, s3)
        s0 << r3
      end
      if s0.last
        r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
        r0.extend(ObsFWS1)
      else
        @index = i0
        r0 = nil
      end

      node_cache[:obs_FWS][start_index] = r0

      r0
    end