myString = "<text contains this>"
myOtherString = "AnotherString"
# Casting to string is not needed but it's good practice
# to check for errors
if str(myString) in str(myOtherString):
# Do Something
else:
# myOtherString didn't contain myString
if any(ext in url_string for ext in extensionsToCheck):
print(url_string)