code: def help_content(self):
          
          message = m.Message()
          message.add(m.Paragraph(tr(
              'In this wizard step: {step_name}, You can choose a exposure '
              'layer from the list of layers that have been loaded to QGIS and '
              'that matches with the geometry and exposure type you set in the '
              'previous step').format(step_name=self.step_name)))
          return message
docs: Return the content of help for this step wizard.
  
              We only needs to re-implement this method in each wizard step.
  
          :returns: A message object contains help.
          :rtype: m.Message