Modularize master branch.

subtract.js

@@ -0,0 +1,22 @@
+import createMathOperation from './_createMathOperation.js';
+
+/**
+ * Subtract two numbers.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Math
+ * @param {number} minuend The first number in a subtraction.
+ * @param {number} subtrahend The second number in a subtraction.
+ * @returns {number} Returns the difference.
+ * @example
+ *
+ * _.subtract(6, 4);
+ * // => 2
+ */
+var subtract = createMathOperation(function(minuend, subtrahend) {
+  return minuend - subtrahend;
+}, 0);
+
+export default subtract;