title: Change toString format of data class
body: <p>I have list of custom object name as <code>Days</code> which 3 properties <code>key</code>,<code>value</code> and <code>isChecked</code>.
  Here is List of Days as Follows:</p>
  <pre><code>    listOf(
           Days(&quot;monday&quot;,&quot;9:30&quot;,false),
           Days(&quot;Tuesday&quot;,&quot;9:30&quot;,true)
           )
  </code></pre>
  <p>output : <code>[Days(key=Monday, value=9:30 AM, isChecked=true), Days(key=Tuesday, value=9:30 AM, isChecked=true)]</code></p>
  <p>data Class:</p>
  <pre><code>data class Days(
      val key: String,
      var value: String,
      var isChecked:Boolean
  )
  </code></pre>
  <p>Now I do not want to print the last properties of each object i,e <code>isChecked=true</code> or <code>isChecked=false</code>..How can i achieve that . I have tried <code>filter</code> and <code>map</code> lambdas but did not get desired result.</p>
  <p>Expected o/p : <code>[Days(key=Monday, value=9:30 AM), Days(key=Tuesday, value=9:30 AM)]</code></p>