Improve code quality and write tests

node_modules/lodash/_baseIsRegExp.js

@@ -0,0 +1,18 @@
+var baseGetTag = require('./_baseGetTag'),
+    isObjectLike = require('./isObjectLike');
+
+/** `Object#toString` result references. */
+var regexpTag = '[object RegExp]';
+
+/**
+ * The base implementation of `_.isRegExp` without Node.js optimizations.
+ *
+ * @private
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is a regexp, else `false`.
+ */
+function baseIsRegExp(value) {
+  return isObjectLike(value) && baseGetTag(value) == regexpTag;
+}
+
+module.exports = baseIsRegExp;