class Rouge::Formatter

def self.find(tag)

def self.find(tag)
  REGISTRY[tag]
end

def self.tag(tag=nil)

def self.tag(tag=nil)
  return @tag unless tag
  REGISTRY[tag] = self
  @tag = tag
end

def render(tokens)

def render(tokens)
  enum_for(:stream, tokens).to_a.join
end

def stream(tokens, &b)

def stream(tokens, &b)
  raise 'abstract'
end