After discussing this issue on github with the creator of the project - magmax (here), I understood that readchar package works only if you try to run it from a terminal but not from any IDE or other non terminal executions. The error is caused because it tries to get the terminal settings which is non existent in this case.

I have been trying to run it from an Wing IDE. The program works great if you try to run it from a terminal.

P.S: magmax suggested to use readchar.keys.ENTER instead of \r . And suggested to have a look at https://github.com/magmax/python-inquirer & its examples

Here's a link to the ActiveState Recipes site that says how you can read a single character in Windows, Linux and OSX:

    getch()-like unbuffered character reading from stdin on both Windows and Unix

class _Getch:
    """Gets a single character from standard input.  Does not echo to the
screen."""
    def __init__(self):
        try:
            self.impl = _GetchWindows()
        except ImportError:
            self.impl = _GetchUnix()

    def __call__(self): return self.impl()


class _GetchUnix:
    def __init__(self):
        import tty, sys

    def __call__(self):
        import sys, tty, termios
        fd = sys.stdin.fileno()
        old_settings = termios.tcgetattr(fd)
        try:
            tty.setraw(sys.stdin.fileno())
            ch = sys.stdin.read(1)
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
        return ch


class _GetchWindows:
    def __init__(self):
        import msvcrt

    def __call__(self):
        import msvcrt
        return msvcrt.getch()


getch = _Getch()