to_string
Description:
Prints the section into a human-readable text form using [method@Gtk.
CssSection.print].
Parameters:
| this | 
           a `GtkCssSection`  | 
      
Returns:
| 
           A new string.  | 
      
Prints the section into a human-readable text form using [method@Gtk.
CssSection.print].
| this | 
           a `GtkCssSection`  | 
      
| 
           A new string.  |