default kwargs are evaluated at definition time

This stackoverflow question covers the topic pretty well:

    http://stackoverflow.com/q/1132941/1547030

From docs.python.org:

    Default parameter values are evaluated when the function definition is
    executed. This means that the expression is evaluated once, when the
    function is defined, and that the same “pre-computed” value is used for
    each call. This is especially important to understand when a default
    parameter is a mutable object, such as a list or a dictionary: if the
    function modifies the object (e.g. by appending an item to a list), the
    default value is in effect modified. This is generally not what was
    intended. A way around this is to use None as the default, and
    explicitly test for it in the body of the function

Author: stavxyz

pythonwhois/net.py

@@ -2,7 +2,9 @@
 from codecs import encode, decode
 from . import shared
 
-def get_whois_raw(domain, server="", previous=[], rfc3490=True, never_cut=False, with_server_list=False, server_list=[]):
+def get_whois_raw(domain, server="", previous=None, rfc3490=True, never_cut=False, with_server_list=False, server_list=None):
+	previous = previous or []
+	server_list = server_list or []
 	# Sometimes IANA simply won't give us the right root WHOIS server
 	exceptions = {
 		".ac.uk": "whois.ja.net",
@@ -20,7 +22,6 @@ def get_whois_raw(domain, server="", previous=[], rfc3490=True, never_cut=False,
 
 	if len(previous) == 0 and server == "":
 		# Root query
-		server_list = [] # Otherwise it retains the list on subsequent queries, for some reason.
 		is_exception = False
 		for exception, exc_serv in exceptions.items():
 			if domain.endswith(exception):

pythonwhois/parse.py

@@ -426,7 +426,8 @@ def is_string(data):
 		return isinstance(data, str)
 
 
-def parse_raw_whois(raw_data, normalized=[], never_query_handles=True, handle_server=""):
+def parse_raw_whois(raw_data, normalized=None, never_query_handles=True, handle_server=""):
+	normalized = normalized or []
 	data = {}
 
 	raw_data = [segment.replace("\r", "") for segment in raw_data] # Carriage returns are the devil
@@ -995,4 +996,4 @@ def parse_nic_contact(data):
 			for match in matches:
 				handle_contacts.append(match.groupdict())
 
-	return handle_contacts
+	return handle_contacts