class RDoc::Markdown

def get_line(no)
  loff = position_line_offsets
  if no < 0
    raise "Line No is out of range: #{no} < 0"
  elsif no >= loff.size
    raise "Line No is out of range: #{no} >= #{loff.size}"
  end
  lend = loff[no]-1
  lstart = no > 0 ? loff[no-1] : 0
  string[lstart..lend]
end