# 3. replace ':' with '.' inside parts
# 3. join parts using '.'
hrn = '.'.join([Xrn.escape(part).replace(':','.') for part in parts if part])
# 3. replace ':' with '.' inside parts
# 3. join parts using '.'
hrn = '.'.join([Xrn.escape(part).replace(':','.') for part in parts if part])