new_contents: #!/usr/bin/env python
  
  import sys
  
  
  try:
      wf_name = str(sys.argv[1])
      branch_cnt = int(sys.argv[2])
      branch_depth = int(sys.argv[3])
  
      add_join = len(sys.argv) > 4
  except:
      raise ValueError(
          'Usage: <script_name> workflow_name'
          ' number_of_parallel_branches branch_depth add_join'
      )
  
  
  f = open('%s.mist' % wf_name, 'w')
  
  # Writing a workflow header to the file.
  
  f.write('---\n')
  f.write("version: '2.0'\n\n")
  
  f.write("%s:\n" % wf_name)
  f.write("  tasks:\n")
  
  # 1. First starting task.
  
  f.write("    task_1:\n")
  f.write("      action: std.noop\n")
  f.write("      on-success:\n")
  
  for branch_num in range(1, branch_cnt + 1):
      f.write("        - task_%s_1\n" % branch_num)
  
  # 2. Branch tasks.
  
  for branch_num in range(1, branch_cnt + 1):
      for task_num in range(1, branch_depth + 1):
          f.write("    task_%s_%s:\n" % (branch_num, task_num))
          f.write("      action: std.noop\n")
  
          if task_num < branch_depth:
              f.write("      on-success: task_%s_%s\n" % (branch_num, task_num + 1))
          elif add_join:
              f.write("      on-success: task_join\n")
  
  # 3. The last "join" task, if needed.
  
  if add_join:
      f.write("    task_join:\n")
      f.write("      join: all")
  
  f.close()
  
  print("Workflow '%s' is created." % wf_name)
  
subject: Add a script that generates a test workflow with needed paralellism