title: How to remove multiple keys from a Map dynamically
body: <p>Say I have a map like this:</p>
  
  <pre><code>scala&gt; val a = Map("a"-&gt;2, "d" -&gt; 4, "r" -&gt; 5)
  a: scala.collection.immutable.Map[String,Int] = Map(a -&gt; 2, d -&gt; 4, r -&gt; 5)
  </code></pre>
  
  <p>I want to remove multiple keys dynamically from this. While I am able to do this:</p>
  
  <pre><code>scala&gt; a - ("a","r")
  res13: scala.collection.immutable.Map[String,Int] = Map(d -&gt; 4)
  </code></pre>
  
  <p>But following fails:</p>
  
  <pre><code>scala&gt; val keys = ("d","r")
  as: (String, String) = (d,r)
  
  scala&gt; a - keys
  &lt;console&gt;:15: error: type mismatch;
   found   : (String, String)
   required: String
         a - keys
             ^
  </code></pre>
  
  <p>While I understand this will be some casting issue, but I am not able to figure this simple thing out.</p>
  
  <h2>Edit</h2>
  
  <p>I also tried to make <code>keys</code> as array, as in earlier example it became a Tuple, but that also fails.</p>
  
  <pre><code>scala&gt; val keys = Array("d","r")
  as: Array[String] = Array(d, r)
  
  scala&gt; a - keys
  &lt;console&gt;:15: error: type mismatch;
   found   : Array[String]
   required: String
         a - keys
             ^
  </code></pre>