input: Write a function to create a BPMN diagram for FOMDES process 1 using Python and the bpmn_pgv library. The diagram should include clusters for Secretaría Ejecutiva, Presidencia, and Presupuesto/Administración, with specific tasks and edges defined within each cluster. Additionally, include nodes for SIGEFOMDES Administración and SISAC, and connect them to the appropriate clusters using dashed edges. Finally, save the diagram as a PNG file named "proc4.png" and a DOT file named "proc4.dot".
  assert create_bpmn_diagram() is None
output: def create_bpmn_diagram():
      import bpmn_pgv as bpmn
  
      g = bpmn.BPMNGraph()
  
      # Secretaría Ejecutiva cluster
      g.add_cluster(bpmn.BPMNCluster("Secretaría Ejecutiva"))
      g.add_node("Secretaría Ejecutiva", "Task1", "Task")
      g.add_node("Secretaría Ejecutiva", "Task2", "Task")
      g.add_edge("Task1", "Task2")
  
      # Presidencia cluster
      g.add_cluster(bpmn.BPMNCluster("Presidencia"))
      g.add_node("Presidencia", "Task3", "Task")
      g.add_node("Presidencia", "Task4", "Task")
      g.add_edge("Task3", "Task4")
  
      # Presupuesto/Administración cluster
      g.add_cluster(bpmn.BPMNCluster("Presupuesto/Administración"))
      g.add_node("Presupuesto/Administración", "Task5", "Task")
      g.add_node("Presupuesto/Administración", "Task6", "Task")
      g.add_edge("Task5", "Task6")
  
      # Nodes outside clusters
      g.add_node("SIGEFOMDES Administración", "Task7", "Task")
      g.add_node("SISAC", "Task8", "Task")
  
      # Dashed edges
      g.add_edge("Task7", "Task1", style="dashed")
      g.add_edge("Task8", "Task3", style="dashed")
  
      # Save the diagram
      g.write_png("proc4.png")
      g.write_dot("proc4.dot")
  
      return None