get the next character, excluding comments. peek() is used to see
           if a '/' is followed by a '/' or '*'.

def _next(self):
        """get the next character, excluding comments. peek() is used to see
           if a '/' is followed by a '/' or '*'.
        """
        c = self._get()
        if c == '/':
            p = self._peek()
            if p == '/':
                c = self._get()
                while c > '\n':
                    c = self._get()
                return c
            if p == '*':
                c = self._get()
                while 1:
                    c = self._get()
                    if c == '*':
                        if self._peek() == '/':
                            self._get()
                            return ' '
                    if c == '\000':
                        raise UnterminatedComment()

        return c