# File lib/asciidoctor/reader.rb, line 230
  def peek_line(preprocess = true)
    if !preprocess
      # QUESTION do we need to dup?
      @eof || (@eof = @lines.empty?) ? nil : @lines.first.dup
    elsif has_more_lines?
      # QUESTION do we need to dup?
      @lines.first.dup
    else
      nil
    end
  end