code: def getlines(filename, opts=default_opts):
      
      if get_option('reload_on_change', opts): checkcache(filename)
      fmt = get_option('output', opts)
      highlight_opts = {'bg': fmt}
      cs = opts.get('style')
  
      # Colorstyle of Terminal255Formatter takes precidence over
      # light/dark colorthemes of TerminalFormatter
      if cs:
          highlight_opts['style'] = cs
          fmt = cs
  
      if filename not in file_cache:
          update_cache(filename, opts)
          filename = pyc2py(filename)
          if filename not in file_cache: return None
          pass
      lines = file_cache[filename].lines
      if fmt not in lines.keys():
          lines[fmt] = highlight_array(lines['plain'], **highlight_opts)
          pass
      return lines[fmt]
docs: Read lines of *filename* and cache the results. However, if
      *filename* was previously cached use the results from the
      cache. Return *None* if we can not get lines