import sys
from string import printable
import termios
import tty

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)
            ch = sys.stdin.read(1)[0]
        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()

# enter: ord 13
#backspace: ord 127

current_input = ""
prompt_msg = ":> "

print(10*"n"+prompt_msg,end="")

getch = _Getch()

def clear_input():
    linelen = (len(current_input)+len(prompt_msg))
    sys.stdout.write("b"*linelen+" "*linelen+"b"*linelen)
    sys.stdout.flush()


while(True):

    ch=getch()
    if ord(ch)==3:# ctrl+c
        exit()
    # >>>>>>>.POINT OF INTEREST<<<<<<<<<<<
    if ord(ch)==13:# enter
        clear_input()
        print(current_input)
        current_input = ""

        # print(prompt_msg,end="")
        sys.stdout.write(prompt_msg)
        sys.stdout.flush()

    if ord(ch)==127 and len(current_input)>0:# backspace
        sys.stdout.write("b"+" "+"b")
        sys.stdout.flush()
        current_input=current_input[:-1]
    if ch in printable or ord(ch)>127: # printable
        current_input+=ch
        sys.stdout.write(ch)
        sys.stdout.flush()