code: function hash_password(plain_text, salt, callback) {
    // Get the crypto library.
    const crypto = require("crypto")
  
    // These should be a *slow* as possible, higher = slower.
    // Slow it down until you tweak a bounce change.
    const password_iterations = process.env.PW_GEN_PW_ITERS || 4096
  
    // Password length and algorithm.
    const password_length = process.env.PW_GEN_PW_LENGTH || 512
    const password_algorithm = process.env.PW_GEN_PW_ALG || "sha256"
  
    // Create a hash, we're going to encrypt the password.
    // I wish Node had native support for good KDF functions
    // like bcrypt or scrypt but PBKDF2 is good for now.
    crypto.pbkdf2(plain_text, salt, password_iterations, password_length, password_algorithm, (err, key) => {
      // Move on.
      callback(key.toString("hex"), salt)
    })
  }
docs: Hash a plain string with the salt and call the callback.
  @param  {String}   plain_text to hash.
  @param  {String}   salt to use during hash process.
  @param  {Function} callback to execute with the new password.
  @return {void}