Added When Example

010-when

@@ -0,0 +1,27 @@
+pipeline {
+    agent any
+    parameters {
+        choice(name: 'OS', choices: ['android', 'ios'], description: 'Pick your OS something')
+    }
+    environment {
+        ENV     = "$OS"
+    }
+    stages {
+        stage ('Deploy ANDROID') {
+            when {
+                environment name: "ENV", value: "android"
+            }
+            steps {
+                echo 'Android execution'
+            }
+        }
+        stage ('Deploy IOS') {
+            when {
+                environment name: "ENV", value: "ios"
+            }
+            steps {
+                echo 'ios execution'
+            }
+        }
+    }
+}