How to use the pexpect.replwrap.REPLWrapper function in pexpect

def run_command(self, demo, command=None):
        """
        Run the demo.curent_command unless command is passed in, in
        which case run the supplied command in the current demo
        encironment.
        """
        if not self.shell:
            child = pexpect.spawnu('/bin/bash', env=demo.env.get(), echo=False, timeout=None)
            ps1 = PEXPECT_PROMPT[:5] + u'\[\]' + PEXPECT_PROMPT[5:]
            ps2 = PEXPECT_CONTINUATION_PROMPT[:5] + u'\[\]' + PEXPECT_CONTINUATION_PROMPT[5:]
            prompt_change = u"PS1='{0}' PS2='{1}' PROMPT_COMMAND=''".format(ps1, ps2)
            self.shell = pexpect.replwrap.REPLWrapper(child, u'\$', prompt_change)

        if not command:
            command = demo.current_command

        print(colorama.Fore.GREEN+colorama.Style.BRIGHT)
        response = self.shell.run_command(command)
        print(response)
        print(colorama.Style.RESET_ALL)
        return response

def get_shell(self):
        """Gets or creates the shell in which to run commands for the
        supplied demo
        """
        if self._shell == None:
            #  Should we use spawn or spawnu?
            child = pexpect.spawnu('/bin/bash', env=self._env, echo=False, timeout=None)
            ps1 = PEXPECT_PROMPT[:5] + u'\[\]' + PEXPECT_PROMPT[5:]
            ps2 = PEXPECT_CONTINUATION_PROMPT[:5] + u'\[\]' + PEXPECT_CONTINUATION_PROMPT[5:]
            prompt_change = u"PS1='{0}' PS2='{1}' PROMPT_COMMAND=''".format(ps1, ps2)
            self._shell = pexpect.replwrap.REPLWrapper(child, u'\$', prompt_change)
        return self._shell

def _start_idl(self):
        # Signal handlers are inherited by forked processes, and we can't easily
        # reset it from the subprocess. Since kernelapp ignores SIGINT except in
        # message handlers, we need to temporarily reset the SIGINT handler here
        # so that IDL and its children are interruptible.
        sig = signal.signal(signal.SIGINT, signal.SIG_DFL)
        try:
            self._executable = find_executable("idl")
            self._child  = spawn(self._executable,timeout = 300)
            self.idlwrapper = replwrap.REPLWrapper(self._child,u"IDL> ",None)
        except:
            self._executable = find_executable("gdl")
            self._child  = spawn(self._executable,timeout = 300)
            self.idlwrapper = replwrap.REPLWrapper(self._child,u"GDL> ",None)
        finally:
            signal.signal(signal.SIGINT, sig)

        self.idlwrapper.run_command("!quiet=1 & defsysv,'!inline',0 & !more=0".rstrip(), timeout=None)
        # Compile IDL routines/functions
        dirname = os.path.dirname(os.path.abspath(__file__))
        self.idlwrapper.run_command(".compile "+dirname+"/snapshot.pro",timeout=None)

def get_shell(self):
        """Gets or creates the shell in which to run commands for the
        supplied demo
        """
        if self._shell == None:
            child = pexpect.spawnu('/bin/bash', env=self.demo.env.get(), echo=False, timeout=None)
            ps1 = PEXPECT_PROMPT[:5] + u'\[\]' + PEXPECT_PROMPT[5:]
            ps2 = PEXPECT_CONTINUATION_PROMPT[:5] + u'\[\]' + PEXPECT_CONTINUATION_PROMPT[5:]
            prompt_change = u"PS1='{0}' PS2='{1}' PROMPT_COMMAND=''".format(ps1, ps2)
            self._shell = pexpect.replwrap.REPLWrapper(child, u'\$', prompt_change)
        return self._shell