def _escape_sequence(self, char):
        """
        Handle characters seen when in an escape sequence. Most non-vt52
        commands start with a left-bracket after the escape and then a 
        stream of parameters and a command.
        """

        num = ord(char)
        if char == "[":
            self.state = "escape-lb"
        elif char == "(":
            self.state = "charset-g0"
        elif char == ")":
            self.state = "charset-g1"
        elif num in self.escape:
            self.dispatch(self.escape[num])
            self.state = "stream"
        elif self.fail_on_unknown_esc:
            raise StreamProcessError("Unexpected character '%c' == '0x%02x'" % (char, ord(char)))
Handle characters seen when in an escape sequence. Most non-vt52
        commands start with a left-bracket after the escape and then a 
        stream of parameters and a command.