src/MarkdownFactory.php
public function addBlockPlugins($firstLetter, array $blockNameCollection)
    {
        if (isset($this->blockPlugins[$firstLetter])) {
            $mergedPlugins = array_merge(
                $this->blockPlugins[$firstLetter],
                $blockNameCollection
            );

            $this->blockPlugins[$firstLetter] = array_unique($mergedPlugins);

            return $this;
        }

        $this->blockPlugins[$firstLetter] = $blockNameCollection;

        return $this;
    }
public function addBlockPlugins($firstLetter, array $blockNameCollection)
    {
        if (isset($this->blockPlugins[$firstLetter])) {
            $mergedPlugins = array_merge(
                $this->blockPlugins[$firstLetter],
                $blockNameCollection
            );

            $this->blockPlugins[$firstLetter] = array_unique($mergedPlugins);

            return $this;
        }

        $this->blockPlugins[$firstLetter] = $blockNameCollection;

        return $this;
    }
@param string $firstLetter
@param array $blockNameCollection

@return $this