import os
import re

for filename in os.listdir(os.getcwd()):
    lowercase_season_regex = r"(summer|winter|spring|fall|autumn)"
    season_matches = re.finditer(lowercase_season_regex, filename, re.MULTILINE | re.IGNORECASE)
    for matchNum, match in enumerate(season_matches, start=1):
        lowercased_season_file_name = filename.replace(match.group(), match.group().lower())
        os.replace(filename, lowercased_season_file_name)