Normalise a search term, at indexing and at query time alike: lower-case, drop English stop words, and reduce the word to its Porter stem, so "cats" matches "cat" and "vaccinated" matches "vaccination".
raw term
processed term, or null to drop it
Normalise a search term, at indexing and at query time alike: lower-case, drop English stop words, and reduce the word to its Porter stem, so "cats" matches "cat" and "vaccinated" matches "vaccination".