diff --git a/apportionment.py b/apportionment.py
index 03dfbda..68f3008 100644
--- a/apportionment.py
+++ b/apportionment.py
@@ -4,8 +4,8 @@ import math
 from fractions import Fraction
 
 
-def method(method, votes, seats, parties=string.letters, threshold=None,
-           verbose=True):
+def method(method, votes, seats, parties=string.ascii_letters,
+           threshold=None, verbose=True):
     filtered_votes = apply_threshold(votes, threshold)
     if method == "quota":
         return quota(filtered_votes, seats, parties, verbose)
@@ -44,7 +44,8 @@ def __print_results(representatives, parties):
 
 # verifies whether a given assignment of representatives
 # is within quota
-def within_quota(votes, representatives, parties=string.letters, verbose=True):
+def within_quota(votes, representatives, parties=string.ascii_letters,
+                 verbose=True):
     n = sum(votes)
     seats = sum(representatives)
     within = True
@@ -67,7 +68,7 @@ def within_quota(votes, representatives, parties=string.letters, verbose=True):
 
 
 # Largest remainder method (Hamilton method)
-def largest_remainder(votes, seats, parties=string.letters,
+def largest_remainder(votes, seats, parties=string.ascii_letters,
                       verbose=True):
     if verbose:
         print("\nLargest remainder method with Hare quota (Hamilton)")
@@ -103,7 +104,7 @@ def largest_remainder(votes, seats, parties=string.letters,
 
 
 # Divisor methods
-def divisor(votes, seats, method, parties=string.letters,
+def divisor(votes, seats, method, parties=string.ascii_letters,
             verbose=True):
     representatives = [0] * len(votes)
     if method in ["dhondt", "jefferson", "greatestdivisors"]:
@@ -216,7 +217,7 @@ def __divzero_fewerseatsthanparties(votes, seats, parties, verbose):
 #  ( see Balinski, M. L., & Young, H. P. (1975).
 #        The quota method of apportionment.
 #        The American Mathematical Monthly, 82(7), 701-730.)
-def quota(votes, seats, parties=string.letters, verbose=True):
+def quota(votes, seats, parties=string.ascii_letters, verbose=True):
     if verbose:
         print("\nQuota method")
     representatives = [0] * len(votes)
diff --git a/examples/nr_wahlen.txt b/examples/nr_wahlen.txt
index 5cb0b10..478c482 100644
--- a/examples/nr_wahlen.txt
+++ b/examples/nr_wahlen.txt
@@ -1,6 +1,6 @@
 (2019,["ÖVP", "SPÖ", "FPÖ", "NEOS", "JETZT", "GRÜNE", "KPÖ", "WANDL", "BZÖ", "BIER", "CPÖ", "GILT", "SLP"], [1789417, 1011868, 772666, 387124, 89169, 664055, 32736, 22168, 760, 4946, 260, 1767, 310], [71, 40, 31, 15, 0, 26, 0, 0, 0, 0, 0, 0, 0])
 (2017, ["SPÖ", "ÖVP", "FPÖ", "GRÜNE", "NEOS", "PILZ", "GILT", "FLÖ", "KPÖ", "WEIßE", "SLP", "EUAUS", "M", "CPÖ", "NBZ", "ODP"], [1361746, 1595526, 1316442, 192638, 268518, 223543, 48234, 8889, 39689, 9167, 713, 693, 221, 425, 2724, 761], [52, 62, 51, 0, 10, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
-(2013, ["SPÖ", "ÖVP", "FPÖ","BZÖ", "GRÜNE", "FRANK", "NEOS", "KPÖ", "PIRAT", "CPÖ", "WANDL", "M", "EUAUS", "SLP"], [1258605, 1125876, 962313, 165746, 582657, 268679, 243946, 48175, 36265, 6647, 3051, 490, 510, 947], [52, 47, 40, 0, 24, 11, 9, 0, 0, 0, 0, 0, 0, 0])
+(2013, ["SPÖ", "ÖVP", "FPÖ","BZÖ", "GRÜNE", "FRANK", "NEOS", "KPÖ", "PIRAT", "CPÖ", "WANDL", "M", "EUAUS", "SLP"], [1258605, 1125876, 962313, 165746, 582657, 268679, 232946, 48175, 36265, 6647, 3051, 490, 510, 947], [52, 47, 40, 0, 24, 11, 9, 0, 0, 0, 0, 0, 0, 0])
 (2008, ["SPÖ", "ÖVP", "GRÜNE", "FPÖ", "BZÖ", "FRITZ", "DC", "KPÖ", "LIF", "RETTÖ", "LINKE", "KLEMENTE", "LINKE", "STARK", "TRP"], [1430206, 1269656, 509936, 857029, 522933, 86194, 31080, 37362, 102249, 35718, 349, 347, 1789, 237, 2224], [57, 51, 20, 34, 21, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])  # LINKE = Die Linke und LINKE = Linke
 (2006, ["ÖVP", "SPÖ", "FPÖ", "GRÜNE", "BZÖ", "KPÖ", "MATIN", "NFÖ", "IVE", "STARK", "SAU", "SLP"], [1616493, 1663986, 519598, 520130, 193539, 47578, 131688, 10594, 592, 312, 1514, 2257], [66, 68, 21, 21, 7, 0, 0, 0, 0, 0, 0, 0])
 (2002, ["SPÖ", "FPÖ", "ÖVP", "GRÜNE", "KPÖ", "LIF", "DD", "CWG", "SLP"], [1792499, 491328, 2076833, 454980, 27568, 48083, 2439, 2009, 3906], [69, 18, 79, 17, 0, 0, 0, 0, 0])