"AssertionError: write() argument must be a bytes instance" when running WSGISOAPHandler

I have a SOAP server with pysimplesoap in Python 3.

Code

from wsgiref.simple_server import make_server

application = WSGISOAPHandler(dispatcher)
wsgid = make_server('', 8008, application)
wsgid.serve_forever()

I don't know why am I get the following error.

Error

Traceback (most recent call last):
  File "/usr/lib/python3.4/wsgiref/handlers.py", line 138, in run
    self.finish_response()
  File "/usr/lib/python3.4/wsgiref/handlers.py", line 180, in finish_response
    self.write(data)
  File "/usr/lib/python3.4/wsgiref/handlers.py", line 266, in write
    "write() argument must be a bytes instance"
AssertionError: write() argument must be a bytes instance

+++ pysimplesoap/server.py  

                     e['name'] = k
                     if array:
                         e[:] = {'minOccurs': "0", 'maxOccurs': "unbounded"}
-                    if v in TYPE_MAP.keys():
-                        t = 'xsd:%s' % TYPE_MAP[v]
-                    elif v is None:
+
+                    # check list and dict first to avoid
+                    # TypeError: unhashable type: 'list' or
+                    # TypeError: unhashable type: 'dict'
+                    if v is None:
                         t = 'xsd:anyType'
                     elif isinstance(v, list):
                         n = "ArrayOf%s%s" % (name, k)
                         n = "%s%s" % (name, k)
                         parse_element(n, v.items(), complex=True)
                         t = "tns:%s" % n
+                    elif v in TYPE_MAP.keys():
+                        t = 'xsd:%s' % TYPE_MAP[v]
                     else:
                         raise TypeError("unknonw type v for marshalling" % str(v))
                     e.add_attribute('type', t)