Add isFunction and isStream helpers

lib/utils.js

@@ -122,6 +122,26 @@ function isBlob(val) {
   return toString.call(val) === '[object Blob]';
 }
 
+/**
+ * Determine if a value is a Function
+ *
+ * @param {Object} val The value to test
+ * @returns {boolean} True if value is a Function, otherwise false
+ */
+function isFunction(val) {
+  return toString.call(val) === '[object Function]';
+}
+
+/**
+ * Determine if a value is a Stream
+ *
+ * @param {Object} val The value to test
+ * @returns {boolean} True if value is a Stream, otherwise false
+ */
+function isStream(val) {
+  return isObject(val) && isFunction(val.pipe);
+}
+
 /**
  * Trim excess whitespace off the beginning and end of a string
  *
@@ -237,6 +257,8 @@ module.exports = {
   isDate: isDate,
   isFile: isFile,
   isBlob: isBlob,
+  isFunction: isFunction,
+  isStream: isStream,
   isStandardBrowserEnv: isStandardBrowserEnv,
   forEach: forEach,
   merge: merge,