code: public function processListItems(Text $list, array $options = array(), $level = 0)
      {
          $list->replace('/\n{2,}\z/', "\n");
  
          /** @noinspection PhpUnusedParameterInspection */
          $list->replace('{
              (\n)?                                 # leading line = $1
              (^[ \t]*)                             # leading whitespace = $2
              (' . $this->getPattern() . ') [ \t]+  # list marker = $3
              ((?s:.+?)                             # list item text   = $4
              (\n{1,2}))
              (?= \n* (\z | \2 (' . $this->getPattern() . ') [ \t]+))
          }mx', function (Text $w, Text $leadingLine, Text $ls, Text $m, Text $item) use ($options, $level) {
              if ((string)$leadingLine || $item->match('/\n{2,}/')) {
                  $this->markdown->emit('outdent', array($item));
                  $this->markdown->emit('block', array($item));
              } else {
                  $this->markdown->emit('outdent', array($item));
                  $this->processList($item, $options, ++$level);
                  $item->rtrim();
                  $this->markdown->emit('inline', array($item));
              }
  
              return $this->getRenderer()->renderListItem($item) . "\n";
          });
      }
docs: Process the contents of a single ordered or unordered list, splitting it into individual list items.
  
  @param Text  $list
  @param array $options
  @param int   $level