# Your previous Plain Text content is preserved below:
# Part 1
# In an HTTP request, the Accept-Language header describes the list of
# languages that the requester would like content to be returned in. The header
# takes the form of a comma-separated list of language tags. For example:
# Accept-Language: en-US, fr-CA, fr-FR
# means that the reader would accept:
# 1. English as spoken in the United States (most preferred)
# 2. French as spoken in Canada
# 3. French as spoken in France (least preferred)
# We're writing a server that needs to return content in an acceptable language
# for the requester, and we want to make use of this header. Our server doesn't
# support every possible language that might be requested (yet!), but there is a
# set of languages that we do support. Write a function that receives two arguments:
# an Accept-Language header value as a string and a set of supported languages,
# and returns the list of language tags that will work for the request. The
# language tags should be returned in descending order of preference (the
# same order as they appeared in the header).
# In addition to writing this function, you should use tests to demonstrate that it's
# correct, either via an existing testing system or one you create.
# Examples:
# parse_accept_language(
# "en-US, fr-CA, fr-FR", # the client's Accept-Language header, a string
# ["fr-FR", "en-US"] # the server's supported languages, a set of strings
# )
# returns: ["en-US", "fr-FR"]
# parse_accept_language("fr-CA, fr-FR", ["en-US", "fr-FR"])
# returns: ["fr-FR"]
# parse_accept_language("en-US", ["en-US", "fr-CA"])
# returns: ["en-US"]
