import json

filename = "username.json"
try:
    with open( filename ) as f:
        username = json.load( f )
except FileNotFoundError:
    username = input( "What is your name?" )
    with open( filename, "w" ) as f:
        json.dump( username, f )
        print( f"We'll remember you when you come back, {username}" )
else:
    print( f"Welcome back, {username}" )
