function XDropWhile(f, xf) {
    this.xf = xf;
    this.f = f;
  }
Returns a new list without any consecutively repeating elements,
based upon the value returned by applying the supplied function to
each list element. [`R.equals`](#equals) is used to determine equality.

Acts as a transducer if a transformer is given in list position.

@func
@memberOf R
@since v0.29.0
@category List
@sig (a -> b) -> [a] -> [a]
@param {Function} fn A function used to produce a value to use during comparisons.
@param {Array} list The array to consider.
@return {Array} `list` without repeating elements.
@see R.transduce
@example

    R.dropRepeatsBy(Math.abs, [1, -1, -1, 2, 3, -4, 4, 2, 2]); //=> [1, 2, 3, -4, 2]