function hashCode (word) {
  let hash = 0
  let chr
  if (word.length === 0) return hash
  for (let i = 0; i < word.length; i++) {
    chr = word.charCodeAt(i)
    hash = (hash << 5) - hash + chr
    hash |= 0 // Convert to 32bit integer
  }
  return hash
}
Compute a hashcode from a given string
@param word : the string, we want to compute the hashcode
@returns {number}: Hascode of the given string