Sanctuary.js is a functional programming library for JavaScript. It's similar to Ramda, but more strict and includes extra features, like the error handling monads Maybe & Either. It's also similar to Folktale, but primarily takes influence from Haskell & PureScript instead of Scala. In this lesson, we use Sanctuary's Traverse and the Maybe monad to safely process lists of data while gaining insight into the relationship between Traverse & Sequence.