```ruby
require 'github/markdown'

module GitHub::HTML
  # HTML Filter that converts Markdown text into HTML and converts into a
  # DocumentFragment. This is different from most filters in that it can take a
  # non-HTML as input. It must be used as the first filter in a pipeline.
  #
  # Context options:
  #   :gfm      => false    Disable GFM line-end processing
  #   :autolink => false    Disable autolinking URLs
  #
  # This filter does not write any additional information to the context hash.
  class MarkdownFilter < Filter
    def initialize(text, context={})
      raise TypeError, "text cannot be HTML" if text.is_a?(DocumentFragment)
      @text = text.to_s.gsub("\r", '')
      super nil, context
    end

    # Convert Markdown to HTML using the best available implementation
    # and convert into a DocumentFragment.
    def call
      flags = [
        :fenced_code, :tables,
        :strikethrough, :lax_htmlblock,
        :gh_blockcode, :no_intraemphasis,
        :space_header
      ]
      flags << :hard_wrap if context[:gfm] != false
      html = GitHub::Markdown.new(@text, *flags).to_html
      html.rstrip!
      html
    end
  end
end
```

Switch to using the Github::Markdown gem
user
```ruby
require 'github/markdown'

module GitHub::HTML
  # HTML Filter that converts Markdown text into HTML and converts into a
  # DocumentFragment. This is different from most filters in that it can take a
  # non-HTML as input. It must be used as the first filter in a pipeline.
  #
  # Context options:
  #   :gfm      => false    Disable GFM line-end processing
  #
  # This filter does not write any additional information to the context hash.
  class MarkdownFilter < Filter
    def initialize(text, context={})
      raise TypeError, "text cannot be HTML" if text.is_a?(DocumentFragment)
      @text = text.to_s.gsub("\r", '')
      super nil, context
    end

    # Convert Markdown to HTML using the best available implementation
    # and convert into a DocumentFragment.
    def call
      mode = (context[:gfm] != false) ? :gfm : :markdown
      GitHub::Markdown.to_html(@text, mode).rstrip!
    end
  end
end
```
assistant