title: How can I define a global variable or constant using jenkins pipeline shared library?
body: <p>While I was able to define methods, defining variables using Jenkins Shared library seems to an unresolved quest so far.</p>
  
  <p>I added <code>/vars/True.groovy</code> with this body</p>
  
  <pre><code>def call() {
      return true
  }
  </code></pre>
  
  <p>And now inside Jenkinsfile, I tried to test if it works as expected:</p>
  
  <pre><code>println "evaluation ${ true == True }"
  </code></pre>
  
  <p>But surprise, this fails as it considers <code>true != class True</code>. My impression is that <code>true == True()</code> may work but that's not the point, I need a real variable because that whole purpose was to avoid some errors caused by people using wrong case.</p>
  
  <p>So what is the magic trick?</p>