title: What is the documentation convention in python for a parameter which is optional only when another parameter is used
body: <p>Let's say I have a function <code>create_person</code> which creates a person object, now let's say I want to give the user the option to either call it with <code>create_person('Tomer', 19, ...)</code> or with <code>create_person(base_person=tomer_person, ...)</code>, how should I document this behavior properly? is this a correct way to define a function?</p>
  <p>Example:</p>
  <pre><code>def create_person(name=None, age=None, base_person=None):
      if not name and not age and base_person:
          person = base_person
      elif not base_person:
          person = Person(name, age)
      ...
  </code></pre>