Destination Zip Code required flag
Clean service name from unsupported strings and characters
Checks whether some request to rates have already been done, so we have cache for it Used to reduce number of same requests done to carrier service during one session
Return USPS county name by country ISO 3166-1-alpha-2 code Return false for unknown countries
Returns cache key for some request to carrier quotes service
Build RateV3 request, send it to USPS gateway and retrieve quotes in XML format
Check is Сoutry U.S. Possessions and Trust Territories
Parse XML string and return XML document object or false
Sets received carrier quotes to cache