Code written in Cross-platform library with __ANDROID__ does not execute in Xamarin forms application

I am using a multi-targeting library in my Xamarin forms application. The library has come code written with __ANDROID__ conditional compiler symbol. When i run the application on Android, it does not execute the code written with the symbol.

The multi-targeting library project is using MSBuild.Sdk.Extras.

<Project Sdk="MSBuild.Sdk.Extras" ToolsVersion="16.0">

  <PropertyGroup>
    <TargetFrameworks>netstandard2.0;MonoAndroid90</TargetFrameworks>
  </PropertyGroup>

I also tried it by defining conditional symbol in Xamarin.Android Project Properties --> Build --> General --> Conditional compilation symbols. But it still does not run that particular code.

#if __ANDROID__
        // do some andoid specific work
#endif

It should run this code block when running the application on Android.

Copyright Notice：Content Author:「Zohaib」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/58237698/code-written-in-cross-platform-library-with-android-does-not-execute-in-xama