Handling 3 operands in an expression without raising an exception

[Νίκος]

Hello,

How can i wrote the two following lines so for NOT to throw out 
KeyErrors when a key is missing?

city = gi.time_zone_by_addr( os.environ['HTTP_CF_CONNECTING_IP'] ) or 
gi.time_zone_by_addr( os.environ['REMOTE_ADDR'] ) or "Άγνωστη Πόλη"

host = socket.gethostbyaddr( os.environ['HTTP_CF_CONNECTING_IP'] )[0] or 
socket.gethostbyaddr( os.environ['REMOTE_ADDR'] )[0] or "Άγνωστη Προέλευση"

I was under the impression that the 'or' operator was handling this in 
case one operand was failing but its not the case here.

I believe in a KeyError is missing the expression cannot even be 
evaluates as Truthy or Falsy.

Then i thought of os.environ.get() to default to something but then 
again we have 3 operand in the expression.