input: Write a function to create a BPMN diagram for FOMDES process 1 using Python and the bpmn_pgv library. The function 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() == "proc4.png and proc4.dot created"
output: 
  def create_bpmn_diagram():
      from bpmn_pgv import BPMN
      g = BPMN()
  
      # Secretaría Ejecutiva cluster
      with g.cluster(name='Secretaría Ejecutiva') as c1:
          task1 = c1.task(name='Task 1')
          task2 = c1.task(name='Task 2')
          c1.edge(task1, task2)
  
      # Presidencia cluster
      with g.cluster(name='Presidencia') as c2:
          task3 = c2.task(name='Task 3')
          task4 = c2.task(name='Task 4')
          c2.edge(task3, task4)
  
      # Presupuesto/Administración cluster
      with g.cluster(name='Presupuesto/Administración') as c3:
          task5 = c3.task(name='Task 5')
          task6 = c3.task(name='Task 6')
          c3.edge(task5, task6)
  
      # Nodes outside clusters
      sigefomdes = g.node(name='SIGEFOMDES Administración')
      sisac = g.node(name='SISAC')
  
      # Dashed edges to clusters
      g.edge(sigefomdes, task1, style='dashed')
      g.edge(sisac, task3, style='dashed')
  
      # Save diagram
      g.draw('proc4.png', format='png')
      g.draw('proc4.dot', format='dot')
  
      return "proc4.png and proc4.dot created"
  