Make tokens argument optional

README.md

@@ -140,6 +140,16 @@ While specifying custom tokens you can also add a symbol-transformation behavior
 }
 ```
 
+## Use mask programmatically
+
+You can use `mask` function directly by importing it (or using `Maska.mask` if you use script tag)
+
+``` javascript
+    import { mask } from 'maska'
+
+    const maskedValue = mask(value, '###')
+```
+
 ## Getting raw (unmasked) value
 
 To get raw value read `data-mask-raw-value` property of input. You can subscribe to `@maska` event to know when this value updates. Please see [examples page](https://beholdr.github.io/maska/).