function tap(value, interceptor) {
      interceptor(value);
      return value;
    }
Invokes `interceptor` with the `value` as the first argument and then
returns `value`. The purpose of this method is to "tap into" a method
chain in order to perform operations on intermediate results within
the chain.

@static
@memberOf _
@category Chaining
@param {*} value The value to provide to `interceptor`.
@param {Function} interceptor The function to invoke.
@returns {*} Returns `value`.
@example

_([1, 2, 3, 4])
 .tap(function(array) { array.pop(); })
 .reverse()
 .value();
// => [3, 2, 1]