module HTTParty::ClassMethods

def format(f = nil)

end
format :json
include HTTParty
class Foo

Must be one of the allowed formats ie: json, xml
Allows setting the format with which to parse. 
def format(f = nil)
  if f.nil?
    default_options[:format]
  else
    parser(Parser) if parser.nil?
    default_options[:format] = f
    validate_format
  end
end