class Sanitize

def clean_document!(html)

were made.
Performs clean_document in place, returning _html_, or +nil+ if no changes 
def clean_document!(html)
  if !@config[:elements].include?('html') && !@config[:remove_contents]
    raise 'You must have the HTML element whitelisted to call #clean_document unless remove_contents is set to true'
    # otherwise Nokogiri will raise for having multiple root nodes when
    # it moves its children to the root document context
  end
  clean!(html, Nokogiri::HTML::Document)
end