Capitalize the first letter of a list of words

capitalizer.py

import sys

def display_help():
    print("USAGE: python ~/tools/capitalizer.py input.txt output.txt\n")
    print("ARGS:")
    print("  [input_file]  -->  Input file containing a list of words")
    print("  [output_file] -->  Output file to write the capitalized words")

# Display help if --help flag is provided or if number of arguments is less than 2
if "--help" in sys.argv or len(sys.argv) < 3:
    display_help()
    sys.exit()

input_file = sys.argv[1]
output_file = sys.argv[2]

# Read words from input file, capitalize if it's not a number and the first character is not already uppercase, and write to output file
with open(input_file, 'r') as f_in, open(output_file, 'w') as f_out:
    first_word = True
    for line in f_in:
        word = line.strip()
        if word and not word.isdigit() and not word[0].isupper():
            word = word.capitalize()
        if first_word:
            first_word = False
        else:
            f_out.write('\n')
        f_out.write(word)