title: Python isinstance returns false. Custom class
body: <p>I have written the following code.</p>
  <pre class="lang-py prettyprint-override"><code>class Mammal:
      def info():
          return 'I have fur on my body.'
  
      def identity_mammal():
          print('I am a mammal')
  
  class Primate(Mammal):
      def info():
          return Mammal.info() + ' I have a large brain.'
  
      def identity_primate():
          print('I am a primate')
  
  class Ape(Primate):
      def info():
          return Primate.info() + ' I am monkey oooh oooh aaah aaah.'
  
      def identity_ape():
          print('I am an ape')
  
  class Human(Primate):
      def info():
          return Primate.info() + ' I am human, me bipedal SMART monkey'
  
      def identity_human():
          print('I am a human')
  
  John = Human
  
  print(isinstance(John, Mammal))
  print(isinstance(John, Primate))
  print(isinstance(John, Human))
  print(isinstance(John, Ape))
  
  </code></pre>
  <p>It is a simple task about inheritance, but when i use the isinstance function, it doesn't seem like the instance of Human i just created is human</p>
  <pre><code>[iveris@ic-rh7mnifi-105 oblig44]$ python3 inheritance.py 
  
  False
  False
  False
  False
  
  </code></pre>