gistfile1.txt

import sys
filename = sys.argv[1]  # first argument
string_to_count = sys.argv[2]  # second argument

with open(filename) as f:  # opens a file, f becomes the file object, this is the official PEP8 style for reading files
    text = f.read()  # we need to read the data from that file
    print(text.count(string_to_count))  # strings have a special function in python that can count the occurrences of a string within them