code: def indentby(parser, token):
      
      args = token.split_contents()
      largs = len(args)
      if largs not in (2, 4):
          raise template.TemplateSyntaxError("indentby tag requires 1 or 3 arguments")
      indent_level = args[1]
      if_statement = None
      if largs == 4:
          if_statement = args[3]
      nodelist = parser.parse(('endindentby', ))
      parser.delete_first_token()
      return IndentByNode(nodelist, indent_level, if_statement)
docs: Add indentation to text between the tags by the given indentation level.
  
      {% indentby <indent_level> [if <statement>] %}
      ...
      {% endindentby %}
  
      Arguments:
        indent_level - Number of spaces to indent text with.
        statement - Only apply indent_level if the boolean statement evalutates to True.