'Implement the CReadableTransport interface for refill'

def cstringio_refill(self, partialread, reqlen):

    retstring = partialread
    if (reqlen < self.DEFAULT_BUFFSIZE):
        retstring += self.read(self.DEFAULT_BUFFSIZE)
    while (len(retstring) < reqlen):
        retstring += self.read((reqlen - len(retstring)))
    self.__rbuf = StringIO(retstring)
    return self.__rbuf
