Check if a list contains incrementing elements starting from zero
<p>I want to check if a list contains incrementing elements, incremented by one each and starting with 0. So, e.g. <code>[0, 1, 2, 3]</code> should return &quot;valid&quot;, whereas e.g. <code>[0, 1, 3, 4]</code> or <code>[-1, 0, 1]</code> should return &quot;not valid&quot;.</p>
<p>Is there an easy way to achieve that in Python? Maybe a built-in function?</p>