What is the Farsi Keyboard application, how does it work?

According to the introduction of Khosrov Boloorian, Farsi Keyboard is a Tools app on the Android platform. There is currently a 5.1 version released on Feb 21, 2019, you can see the details below.

Farsi Keyboard is the best and fastest dual Android keyboard for writing Persian-English with full Persian characters support on just one layout.Farsi Keyboard is designed with most complete features,standard Unicode character set, scientific ,mathematical operators & symbols, theme customization, layout customization -Standard mode and -Full pad mode, fast tapping ,easy to handle,easy fast language switching with high performance and support for Multi-Language such as Farsi (Iran),French,German,Spanish,Italian,Swedish,.....on just one keyboard!
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★Easy wizard-installation with no need for any user setup action
★★Changing language is easier than ever, by just swiping keyboard! or tapping on Language Key.....
★★★Farsi Keyboard is the only compact keyboard with minimum size (700kb) but best performance