Why am I getting this error/how do I fix it?

main.py saved 1 def decrypt (n, text): Python 3.6.1 (default, Dec 2015, 13:05:11) [GCC 4.8.2] on linux Enter the input filename: secret_code.txt Missing text! Traceback (most recent call last): text- [character for character in text] for i in range(0, len (text)): 4 if ord (text[i]) 65 and ord(text[i])