Move internal modules to “internal” folder.

.internal/baseZipObject.js

@@ -0,0 +1,23 @@
+/**
+ * This base implementation of `zipObject` which assigns values using `assignFunc`.
+ *
+ * @private
+ * @param {Array} props The property identifiers.
+ * @param {Array} values The property values.
+ * @param {Function} assignFunc The function to assign values.
+ * @returns {Object} Returns the new object.
+ */
+function baseZipObject(props, values, assignFunc) {
+  let index = -1;
+  const length = props.length;
+  const valsLength = values.length;
+  const result = {};
+
+  while (++index < length) {
+    const value = index < valsLength ? values[index] : undefined;
+    assignFunc(result, props[index], value);
+  }
+  return result;
+}
+
+export default baseZipObject;