function XDrop(n, xf) {
    this.xf = xf;
    this.n = n;
  }
Divides two numbers. Equivalent to `a / b`.

@func
@memberOf R
@since v0.1.0
@category Math
@sig Number -> Number -> Number
@param {Number} a The first value.
@param {Number} b The second value.
@return {Number} The result of `a / b`.
@see R.multiply
@example

     R.divide(71, 100); //=> 0.71

     const half = R.divide(R.__, 2);
     half(42); //=> 21

     const reciprocal = R.divide(1);
     reciprocal(4);   //=> 0.25