import re
regex = re.compile(r"(?<!\w)(?:cat|dog(?:\ and\ cat)?)(?!\w)", flags=re.MULTILINE)
test_str = "I've been bad but I aspire to be a better person, and behave like my dog and cat :)"
subst = "animal"
result = regex.sub(subst, test_str)
if result:
print(result)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html