code: function contains (array, value) {
    if (Array.isArray(array) && !Array.isArray(value)) {
      return array.indexOf(value) > -1
    } else if (Array.isArray(array) && Array.isArray(value)) {
      return value.every(function (item) {
        return contains(array, item)
      })
    } else {
      return array === value
    }
  }
docs: Searches the array for the exact value supplied (strict equality). To query for value existance using an expression or function, use {@link module:array-tools.exists}. If you pass an array of values, contains will return true if they _all_ exist. (note: `exists` returns true if _some_ of them exist).
  
  @param {Array} - the input array
  @param {*} - the value to look for
  @category not chainable
  @return {boolean}
  @static
  @since 1.8.0