return the next character from stdin. Watch out for lookahead. If
           the character is a control character, translate it to a space or
           linefeed.

def _get(self):
        """return the next character from stdin. Watch out for lookahead. If
           the character is a control character, translate it to a space or
           linefeed.
        """
        c = self.theLookahead
        self.theLookahead = None
        if c == None:
            c = self.instream.read(1)
        if c >= ' ' or c == '\n':
            return c
        if c == '': # EOF
            return '\000'
        if c == '\r':
            return '\n'
        return ' '