docs: def execute(self, mold_id, data, wrapper_tag='div'):
          """
          Execute a mold `mold_id` by rendering through ``env``.
  
          This is done using its default template, with data provided as
          dict.
  
          This returns the wrapped content, which contains the bits that
          the client-side on-load script trigger will execute the index.js
          defined for this mold; if this is not desired, simply call the
          render method instead.
          """
  
          template = self.load_mold(mold_id)
  
          kwargs = {}
          kwargs.update(data)
          kwargs['_nunja_data_'] = 'data-nunja="%s"' % mold_id
          kwargs['_template_'] = template
          kwargs['_wrapper_tag_'] = wrapper_tag
  
          return self._core_template_.render(**kwargs)