favouriteOrNot = async (fav_by, user) => {
  let s = await db.query(
    'SELECT COUNT(fav_id) AS fav_count FROM favourites WHERE fav_by=? AND user=?',
    [fav_by, user]
  )
  return db.tf(s[0].fav_count)
}
Returns whether User is fav_by's favorite
@param {Number} fav_by Favorite By
@param {Number} user User ID