Python FQDN Fully-Qualified Domain Names

This package validates Fully Qualified Domain Names (FQDNs) conforming
to the Internet Engineering Task Force specification. The design intent
is to validate that a string would be traditionally acceptable as a 
public Internet hostname to RFC-conforming software, which is a strict
subset of the logic in modern web browsers like Mozilla Firefox and
Chromium that determines whether make a DNS lookup. Configuration
options can relax constraints so that short hostnames without periods
or others with underscores will be valid. These relaxations are closer
to how modern web browsers work.