func NewParallelizer(p int) Parallelizer {
	return Parallelizer{parallelism: p}
}

// chunkSizeFor returns a chunk size for the given number of items to use for
// parallel work. The size aims to produce good CPU utilization.
// returns max(1, min(sqrt(n), n/Parallelism))
func chunkSizeFor(n, parallelism int) int {
	s := int(math.Sqrt(float64(n)))

	if r := n/parallelism + 1; s > r {
		s = r

		{
			input:      0,
			wantOutput: 1,
		},
	}

	for _, test := range tests {
		t.Run(fmt.Sprintf("%d", test.input), func(t *testing.T) {
			if chunkSizeFor(test.input, DefaultParallelism) != test.wantOutput {
				t.Errorf("Expected: %d, got: %d", test.wantOutput, chunkSizeFor(test.input, DefaultParallelism))
			}
		})
	}