title: What is the purpose of 'let' keyword in Kotlin
body: <p>We can write the code with or without <code>let</code> as follows.</p>
  
  <pre><code>var str = "Hello World"
  str.let { println("$it!!") }
  </code></pre>
  
  <p>OR</p>
  
  <pre><code>var str = "Hello World"
  println("$str!!")
  </code></pre>
  
  <p>What is the Actual use of <code>let</code>?.Is that more memory efficient or more readable?</p>