TypeError: unsupported type for timedelta days component: datetime.datetime
<p>I am trying to perform some date arithmetic in a function.</p>

<pre><code>from datetime import datetime, timedelta

def foo(date1, summing_period):
    current_period_start_date = date1 - timedelta(days=summing_period)
    # Line above causes the error:
    # TypeError: unsupported type for timedelta days component: datetime.datetime
</code></pre>

<p>First arg is a datetime obj and 2nd arg is an integer</p>

<p>What is causing this error, and how do I fix it?</p>
