Please answer following questions along with Python code and its result. Make sure to import NLTK.

1. Write a function unknown() that takes a URL as its argument, and returns a list of unknown words that occur on that web page. In order to do this, extract all substrings consisting of lowercase letters (using re.findall()) and remove any items from this set that occur in the Words Corpus (nltk.corpus.words). Try to categorize these words manually and discuss your findings.

2. Use the Porter Stemmer to normalize some tokenized text, calling the stemmer on each word. Do the same thing with the Lancaster Stemmer, and see if you observe any differences.