 <p>Integer or floats values other than 0 are treated as True:</p> <pre><code>In [8]: bool(int(1)) Out[8]: True In [9]: bool(int(0)) Out[9]: False In [10]: bool(int(-1)) Out[10]: True In [16]: bool(float(1.2e4)) Out[16]: True In [17]: bool(float(-1.4)) Out[17]: True In [20]: bool(0.0) Out[20]: False In [21]: bool(0.000001) Out[21]: True </code></pre> <p>Similarly, empty lists, sets, dicts, empty string, None, etc are treated as false:</p> <pre><code>In [11]: bool([]) Out[11]: False In [12]: bool({}) Out[12]: False In [13]: bool(set()) Out[13]: False In [14]: bool("") Out[14]: False In [19]: bool(None) Out[19]: False </code></pre>