title: Scala - How to return a Map value by function?
body: <p>Why below function is not work in scala?</p>
  
  <pre><code>def getUpdatedMap(keywords: String, m: Map[String, String]) : Map[String, String] = {
    m += (keywords -&gt; "abcde")
  }
  </code></pre>
  
  <blockquote>
    <p>Compilation error:
    value += is not a member of Map[String, String]</p>
  </blockquote>
  
  <p>I'm quite new in Scala, any thing I have forget to define or missing?
  Thanks.</p>