+
+def to_bytes(s):
+ if type(s) is bytes:
+ return s
+ elif type(s) is str or (sys.version_info[0] < 3 and type(s) is unicode):
+ return codecs.encode(s, 'utf-8')
+ else:
+ raise TypeError("Expected bytes or string, but got %s." % type(s))
+
+def to_str(s):
+ if type(s) is bytes:
+ return codecs.decode(s, 'utf-8')
+ elif type(s) is str or (sys.version_info[0] < 3 and type(s) is unicode):
+ return s
+ else:
+ raise TypeError("Expected bytes or string, but got %s." % type(s))