class Patron::Session

def handle_cookies(file = nil)

must be readable and writable. Calling multiple times will add more files.
If file is nil they will be stored in memory. Otherwise the +file+
Makes this session handle cookies and store them in in +file+. 
def handle_cookies(file = nil)
  if file
    path = Pathname(file).expand_path
    unless File.exists?(file) and File.writable?(path.dirname)
      raise ArgumentError, "Can't create file #{path} (permission error)"
    end
    unless File.readable?(file) or File.writable?(path)
      raise ArgumentError, "Cant read or write file #{path} (permission error)"
    end
  end
  enable_cookie_session(path.to_s)
  self
end