title: removeWhere in list of files
body: <p>I have a File which contains all the names of all the files I've created and I decode it into a Map which then has the following formate:</p>
  
  <pre><code>{"fileList.json":"false",
  "testwert_0_.json":"false",
  "jakob_0_.json":"false",
  "jakobjokoobus_0_.json":"true",
  "jakobjokoobussss_0_.json":"false",
  "jakobjokoobusssssss_0_.json":"true"}
  </code></pre>
  
  <p>Now I would like to delete all the entries from the map, which have the value set to "true".</p>
  
  <p>It should be a simple problem, but I just can't wrap my head around the map.removeWhere() function.</p>
  
  <p>Could someone please help me with this?</p>