class Fastly::Client

def headers(extras={})
  headers = fully_authed? ? { 'Cookie' => cookie } : {}
  headers['Fastly-Key'] = api_key if api_key
  headers.merge('Content-Accept' => 'application/json', 'User-Agent' => "fastly-ruby-v#{Fastly::VERSION}").merge(extras.keep_if {|k,v| !v.nil? })
end