class Kramdown::Parser::Base

def self.parse(source, options = {})

be implemented by each subclass.
Initializes a new instance of the calling class and then calls the +#parse+ method that must

return the root element of the element tree and an array with warning messages.
Parse the +source+ string into an element tree, possibly using the parsing +options+, and 
def self.parse(source, options = {})
  parser = new(source, options)
  parser.parse
  [parser.root, parser.warnings]
end