usage socketserver for better compatibility with older Python versions

md2html/md2html.py

@@ -4,7 +4,7 @@ import argparse
 import hashlib
 import sys
 import threading
-from http.server import ThreadingHTTPServer, BaseHTTPRequestHandler
+from http.server import BaseHTTPRequestHandler, socketserver, HTTPServer
 from os.path import basename, dirname, abspath, join
 from urllib.parse import urlparse
 
@@ -36,6 +36,10 @@ def compile_html(mdfile=None, extensions=None, raw=None, **kwargs):
     return doc
 
 
+class ThreadingHTTPServer(socketserver.ThreadingMixIn, HTTPServer):
+    pass
+
+
 class MarkdownHTTPServer(ThreadingHTTPServer):
 
     def __init__(self, mdfile, extensions=(), handler=BaseHTTPRequestHandler, interface="127.0.0.1", port=8080):