title: Python method object application
body: <p>What are the advantages of having a python method, like <code>lower()</code>, being applied to an appropriate object, <code>s</code>, via the dot notation (i.e., <code>s.lower()</code>) versus a method, like <code>len()</code>, being also applied appropriately receiving the object as an argument, e.g. <code>len(s)</code> ? If I want to create such a method / function, what are the critical points I should consider choosing the first or the second implementation? Thanks!</p>