docs: def render_descriptor(data):
      """Render data descriptor.
  
      The rendering is based on descriptor schema and input context.
  
      :param data: data instance
      :type data: :class:`resolwe.flow.models.Data` or :class:`dict`
  
      """
      if not data.descriptor_schema:
          return
  
      # Set default values
      for field_schema, field, path in iterate_schema(data.descriptor, data.descriptor_schema.schema, 'descriptor'):
          if 'default' in field_schema and field_schema['name'] not in field:
              dict_dot(data, path, field_schema['default'])