class Nokogiri::HTML::Document

def fragment tags = nil

Create a Nokogiri::XML::DocumentFragment from +tags+
### 
def fragment tags = nil
  DocumentFragment.new(self, tags, self.root)
end

def meta_encoding

then nil is returned
Get the meta tag encoding for this document. If there is no meta tag,
## 
def meta_encoding
  return nil unless meta = css('meta').find { |node|
    node['http-equiv'] =~ /Content-Type/i
  }
  /charset\s*=\s*([\w-]+)/i.match(meta['content'])[1]
end

def meta_encoding= encoding

content tag, nil is returned and the encoding is not set.
Set the meta tag encoding for this document. If there is no meta
## 
def meta_encoding= encoding
  return nil unless meta = css('meta').find { |node|
    node['http-equiv'] =~ /Content-Type/i
  }
  meta['content'] = "text/html; charset=%s" % encoding
  encoding
end

def parse string_or_io, url = nil, encoding = nil, options = XML::ParseOptions::DEFAULT_HTML

Nokogiri::XML::ParseOptions.
Nokogiri::XML::ParseOptions::RECOVER. See the constants in
is a number that sets options in the parser, such as
encoding that should be used when processing the document. +options+
+url+ is resource where this document is located. +encoding+ is the
responds to _read_ and _close_ such as an IO, or StringIO.
Parse HTML. +thing+ may be a String, or any object that
## 
def parse string_or_io, url = nil, encoding = nil, options = XML::ParseOptions::DEFAULT_HTML
  options = Nokogiri::XML::ParseOptions.new(options) if Fixnum === options
  # Give the options to the user
  yield options if block_given?
  if string_or_io.respond_to?(:encoding)
    unless string_or_io.encoding.name == "ASCII-8BIT"
      encoding ||= string_or_io.encoding.name
    end
  end
  if string_or_io.respond_to?(:read)
    url ||= string_or_io.respond_to?(:path) ? string_or_io.path : nil
    return read_io(string_or_io, url, encoding, options.to_i)
  end
  # read_memory pukes on empty docs
  return new if string_or_io.nil? or string_or_io.empty?
  read_memory(string_or_io, url, encoding, options.to_i)
end

def serialize options = {}


end
config.format.as_xml
node.serialize(:encoding => 'UTF-8') do |config|

or

node.serialize(:encoding => 'UTF-8', :save_with => FORMAT | AS_XML)

These two statements are equivalent:

block. See SaveOptions.
Serialize Node using +options+. Save options can also be set using a
### 
def serialize options = {}
  options[:save_with] ||= XML::Node::SaveOptions::FORMAT |
      XML::Node::SaveOptions::AS_HTML |
      XML::Node::SaveOptions::NO_DECLARATION |
      XML::Node::SaveOptions::NO_EMPTY_TAGS
  super
end