def main():
	print("hello, world!")
	x = eval(input("give me a number! "))
	print(x+1,"is my favorite number!!")
main()

Python tells me:
Desktop$ python hello.py
hello, world!
type a word: hi
Traceback (most recent call last):
  File "hello.py", line 7, in <module>
    main()
  File "hello.py", line 3, in main
    x = (input("type a word: "))
  File "<string>", line 1, in <module>
NameError: name 'hi' is not defined