static removeUnique(arr, value) {
    let index = arr.indexOf(value);

    if (index > -1) {
      arr.splice(index, 1);
    }

    return arr;
  }
Remove a value from an array with unique values.

@static
@param {Array} arr An array.
@param {*} value A value to be removed.
@returns {Array} An array with the element with a given value removed.