Bump to v4.0.0.

math.default.js

@@ -0,0 +1,18 @@
+import add from './add';
+import ceil from './ceil';
+import floor from './floor';
+import max from './max';
+import maxBy from './maxBy';
+import mean from './mean';
+import min from './min';
+import minBy from './minBy';
+import round from './round';
+import subtract from './subtract';
+import sum from './sum';
+import sumBy from './sumBy';
+
+export default {
+  add, ceil, floor, max, maxBy,
+  mean, min, minBy, round, subtract,
+  sum, sumBy
+};