title: See if string contains substring
body: <p>I was looking for a way to write code that checks whether a certain string is a part of another string. I understand that it is easy to do when we have numbers, but I don't know how to do it with strings.</p>
  
  <p>For example, I have this function    </p>
  
  <pre><code>a = is_part("motherland", "land")
  </code></pre>
  
  <p>I need to know that <code>"land"</code> is a part of the word <code>"motherland"</code> (return <code>True</code> or <code>False</code>). Is it possible to check this? </p>
  
  <p>UPDATE: How can I create a restriction when the second word always has to be in the end of the first one. For example, in case when I check whether "eight" is a part of "eighteen" it returns False because "eight" is not at the end of the first word</p>