code: def create_virtual_aggregation(geometry, crs):
      
      fields = [
          create_field_from_definition(aggregation_id_field),
          create_field_from_definition(aggregation_name_field)
      ]
      aggregation_layer = create_memory_layer(
          'aggregation', QgsWkbTypes.PolygonGeometry, crs, fields)
  
      aggregation_layer.startEditing()
  
      feature = QgsFeature()
      feature.setGeometry(geometry)
      feature.setAttributes([1, tr('Entire Area')])
      aggregation_layer.addFeature(feature)
      aggregation_layer.commitChanges()
  
      # Generate aggregation keywords
      aggregation_layer.keywords['layer_purpose'] = (
          layer_purpose_aggregation['key'])
      aggregation_layer.keywords['title'] = 'aggr_from_bbox'
      aggregation_layer.keywords[inasafe_keyword_version_key] = (
          inasafe_keyword_version)
      aggregation_layer.keywords['inasafe_fields'] = {
          aggregation_id_field['key']: aggregation_id_field['field_name'],
          aggregation_name_field['key']: aggregation_name_field['field_name']
      }
      # We will fill default values later, according to the exposure.
      aggregation_layer.keywords['inasafe_default_values'] = {}
  
      return aggregation_layer
docs: Function to create aggregation layer based on extent.
  
      :param geometry: The geometry to use as an extent.
      :type geometry: QgsGeometry
  
      :param crs: The Coordinate Reference System to use for the layer.
      :type crs: QgsCoordinateReferenceSystem
  
      :returns: A polygon layer with exposure's crs.
      :rtype: QgsVectorLayer