code: func (p *printer) singleLineList(l *ast.ListType) []byte {
  	buf := &bytes.Buffer{}
  
  	buf.WriteString("[")
  	for i, item := range l.List {
  		if i != 0 {
  			buf.WriteString(", ")
  		}
  
  		// Output the item itself
  		buf.Write(p.output(item))
  
  		// The heredoc marker needs to be at the end of line.
  		if lit, ok := item.(*ast.LiteralType); ok && lit.Token.Type == token.HEREDOC {
  			buf.WriteByte(newline)
  		}
  	}
  
  	buf.WriteString("]")
  	return buf.Bytes()
  }
docs: // singleLineList prints a simple single line list.
  // For a definition of "simple", see isSingleLineList above.