title: How can I determine if a variable exists from within the Groovy code running in the Scripting Engine?
body: <p>How can I determine if a variable exists from within the Groovy code running in the Scripting Engine?</p>
  
  <p>The variable was put by <a href="https://docs.oracle.com/javase/8/docs/api/javax/script/ScriptEngine.html#put(java.lang.String,%20java.lang.Object)" rel="noreferrer">ScriptEngine's put method</a></p>