code: def deserialize_request(self, req):
          
  
          # See if we have a body
          if req.content_length == 0:
              return None
  
          # Get the primary deserializer
          try:
              deserializer = self.method.deserializers(req.content_type)
          except KeyError:
              raise webob.exc.HTTPUnsupportedMediaType()
  
          # If it has an attacher, attach all the deserializers for the
          # extensions
          if hasattr(deserializer, 'attach'):
              for ext in self.extensions:
                  try:
                      deserializer.attach(ext.deserializers(req.content_type))
                  except KeyError:
                      pass
  
          # A deserializer is simply a callable, so call it
          return deserializer(req.body)
docs: Uses the deserializers declared on the action method and its
          extensions to deserialize the request.  Returns the result of
          the deserialization.  Raises `webob.HTTPUnsupportedMediaType`
          if the media type of the request is unsupported.