title: Argument existence by assert statement in python
body: <p>Is there any way to check the existence of argument of a function by assert statement?</p>
  
  <pre><code>def fractional(x) :
      assert x==None, "argument missing"    &lt;---- is it possible here to check?
      assert type(x) == int, 'x must be integer'
      assert x &gt; 0 , ' x must be positive '
      output = 1
      for i in range ( 1 , int(x)+1) :
          output = output*i
      assert output &gt; 0 , 'output must be positive'
      return output 
  y=3
  fractional()   &lt;----- argument missing
  </code></pre>