code: def import_gateway_to_graph(diagram_graph, process_id, process_attributes, element):
          
          element_id = element.getAttribute(consts.Consts.id)
          BpmnDiagramGraphImport.import_flow_node_to_graph(diagram_graph, process_id, process_attributes, element)
          diagram_graph.node[element_id][consts.Consts.gateway_direction] = \
              element.getAttribute(consts.Consts.gateway_direction) \
                  if element.hasAttribute(consts.Consts.gateway_direction) else "Unspecified"
docs: Adds to graph the new element that represents BPMN gateway.
          In addition to attributes inherited from FlowNode type, Gateway
          has additional attribute gatewayDirection (simple type, default value - Unspecified).
  
          :param diagram_graph: NetworkX graph representing a BPMN process diagram,
          :param process_id: string object, representing an ID of process element,
          :param process_attributes: dictionary that holds attribute values of 'process' element, which is parent of
              imported flow node,
          :param element: object representing a BPMN XML element of Gateway type extension.