Returns a wsgi conform list of header/value pairs.

def wsgiheader(self):
        ''' Returns a wsgi conform list of header/value pairs. '''
        for c in self.COOKIES.values():
            if c.OutputString() not in self.headers.getall('Set-Cookie'):
                self.headers.append('Set-Cookie', c.OutputString())
        # rfc2616 section 10.2.3, 10.3.5
        if self.status in (204, 304) and 'content-type' in self.headers:
            del self.headers['content-type']
        if self.status == 304:
            for h in ('allow', 'content-encoding', 'content-language',
                      'content-length', 'content-md5', 'content-range',
                      'content-type', 'last-modified'): # + c-location, expires?
                if h in self.headers:
                     del self.headers[h]
        return list(self.headers.iterallitems())