def get_all_gateways(bpmn_graph):
gateways = filter(lambda node: node[<NUM_LIT:1>]['<STR_LIT:type>'] in GATEWAY_TYPES, bpmn_graph.get_nodes())<EOL>return gateways<EOL>
Returns a list with all gateways in diagram

:param bpmn_graph: an instance of BpmnDiagramGraph representing BPMN model.
:return: a list with all gateways in diagram