code: function hash (str) {
    return crypto
      .createHash('sha1')
      .update(str, 'ascii')
      .digest('base64')
      .replace(PLUS_GLOBAL_REGEXP, '-')
      .replace(SLASH_GLOBAL_REGEXP, '_')
      .replace(EQUAL_GLOBAL_REGEXP, '')
  }
docs: Hash a string with SHA1, returning url-safe base64
  @param {string} str
  @private