Write a sorting function that takes in an array of names and sorts them by last name either alphabetically (ASC) or reverse-alphabetically (DESC).

Examples

sort_contacts([
  "John Locke",
  "Thomas Aquinas",
  "David Hume",
  "Rene Descartes"
], "ASC") ➞ [
  "Thomas Aquinas",
  "Rene Descartes",
  "David Hume",
  "John Locke"
]

# Aquinas (A) < Descartes (D) < Hume (H) < Locke (L)

sort_contacts([
  "Paul Erdos",
  "Leonhard Euler",
  "Carl Gauss"
], "DESC") ➞ [
  "Carl Gauss",
  "Leonhard Euler",
  "Paul Erdos"
]

# Gauss (G) > Erdos (ER) > Euler (EU)

sort_contacts([], "DESC") ➞ []

sort_contacts(null, "DESC") ➞ []

sort_contacts(undefined, "DESC") ➞ []

Notes

• An array with a single name should be trivially returned.
• An empty array, or an input of nil should return an empty array.