code: def import_dashboards(self):
          
          f = request.files.get('file')
          if request.method == 'POST' and f:
              dashboard_import_export.import_dashboards(db.session, f.stream)
              return redirect('/dashboard/list/')
          return self.render_template('superset/import_dashboards.html')
docs: Overrides the dashboards using json instances from the file.