docs: def render_field(self, field, render_kw):
          """
          Returns the rendered field after adding auto–attributes.
  
          Calls the field`s widget with the following kwargs:
  
          1. the *render_kw* set on the field are used as based
          2. and are updated with the *render_kw* arguments from the render call
          3. this is used as an argument for a call to `get_html5_kwargs`
          4. the return value of the call is used as final *render_kw*
  
          """
          field_kw = getattr(field, 'render_kw', None)
          if field_kw is not None:
              render_kw = dict(field_kw, **render_kw)
          render_kw = get_html5_kwargs(field, render_kw)
          return field.widget(field, **render_kw)