text: #!/usr/bin/env python
  """This module executes all notebooks.
  
  It serves the main purpose to ensure that all can be executed and work proper
  independently.
  """
  import glob
  import os
  import subprocess as sp
  
  os.chdir(os.environ["PROJECT_ROOT"] + "/lectures")
  dir_list = glob.glob("*-*")
  dir_list.append("introduction")
  
  for dir_ in dir_list:
  
      os.chdir(dir_)
  
      for notebook in sorted(glob.glob("*.ipynb")):
          cmd = " jupyter nbconvert --to html --execute {}  --ExecutePreprocessor.timeout=-1".format(
              notebook
          )
          sp.check_call(cmd, shell=True)
  
      os.chdir("../")
  