docs: def parse_plain_scalar_indent(TokenClass):
      """Process indentation spaces in a plain scalar."""
      def callback(lexer, match, context):
          text = match.group()
          if len(text) <= context.indent:
              context.stack.pop()
              context.stack.pop()
              return
          if text:
              yield match.start(), TokenClass, text
              context.pos = match.end()
      return callback