code: function inject_dedent(offside_lines, trailing_types) {
    if  ('function' !== typeof trailing_types) {
      const s_trailing_types = new Set(
        trailing_types || ['comment_eol']);
      trailing_types = k => s_trailing_types.has(k);}
  
    for (const ln of offside_lines) {
      if (ln.is_blank) {continue}
  
      const {len_dedent, len_indent, len_inner} = ln;
  
      const offside_dedent ={
        type: 'offside_dedent'
      , len_dedent, len_indent};
  
      if (len_inner) {
        offside_dedent.len_inner = len_inner;}
  
      const last = ln.content.pop();
      if (last.multiline || trailing_types(last.type)) {
        ln.content.push(offside_dedent, last); }
      else {
        ln.content.push(last, offside_dedent); } } }
docs: global regexp