convert declarative pipeline to scripted pipeline

I already used the following declarative script as a part of my cleanup script, now I should convert it to the scripted pipeline, how I can convert the post to the scripted pipeline?

stages {
stage ('Cleanup Feature Releases') {
    agent any
    steps {
        script {
            envParameters = Utils.getEnvParameters("${TARGET_ENV}")
            withKubeConfig([credentialsId: envParameters.K8S_TOKEN,
                            serverUrl: envParameters.K8S_API_SERVER,
                            contextName: CONTEXT_NAME
            ]) {
                sh "Running on ${params.OVERRIDE_NAMESPACE}"
            }
        }
    }
    post {
        failure {
            cleanUpNotification("FAILURE", params.DRY_RUN)
        }
        aborted {
            cleanUpNotification("ABORTED", params.DRY_RUN)
        }
        success {
            cleanUpNotification("SUCCESS", params.DRY_RUN)
        }
    }
}

}

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Author: Mkash