user_input.py

def say_hello():
  print("Hello")
  
def say_bye():
  print("Bye")
  
def say_sup():
  print("Sup?")

  
choice_lookup = {
  "hello": say_hello,
  "bye": say_bye,
  "sup": say_sup,
}
  
user_choice = input("What do you want the computer to say? [ hello / bye / sup ]: ")

try:
  chosen_func = choice_lookup[user_choice]
  chosen_func()
except KeyError:
  print("Error: you can only choose hello / bye / sup")