title: Check for letter after a substring
body: <p>I'm trying to find a way to check whether or not an alpha-numeric character follows a portion of a string. For example, if the sub-string is: <code>sub</code>, and the text is: <code>substrings are cool</code>, it should return <code>True</code> and if the text is: <code>sub dafdgnjgf</code> it should return <code>False</code>.</p>