Python: How do I get key/value pairs from the BaseHTTPRequestHandler HTTP POST handler?

def do_POST(self):
    ctype, pdict = cgi.parse_header(self.headers.getheader('content-type'))
    if ctype == 'multipart/form-data':
        postvars = cgi.parse_multipart(self.rfile, pdict)
    elif ctype == 'application/x-www-form-urlencoded':
        length = int(self.headers.getheader('content-length'))
        postvars = cgi.parse_qs(self.rfile.read(length), keep_blank_values=1)
    else:
        postvars = {}
    ...

I tried to edit the post and got rejected, so there's my version of this code that should work on Python 2.7 and 3.2:

from sys import version as python_version
from cgi import parse_header, parse_multipart

if python_version.startswith('3'):
    from urllib.parse import parse_qs
    from http.server import BaseHTTPRequestHandler
else:
    from urlparse import parse_qs
    from BaseHTTPServer import BaseHTTPRequestHandler

class RequestHandler(BaseHTTPRequestHandler):

    ...

    def parse_POST(self):
        ctype, pdict = parse_header(self.headers['content-type'])
        if ctype == 'multipart/form-data':
            postvars = parse_multipart(self.rfile, pdict)
        elif ctype == 'application/x-www-form-urlencoded':
            length = int(self.headers['content-length'])
            postvars = parse_qs(
                    self.rfile.read(length), 
                    keep_blank_values=1)
        else:
            postvars = {}
        return postvars

    def do_POST(self):
        postvars = self.parse_POST()
        ...

    ...