old_contents: #!/usr/bin/env python
  
  import runpy
  import os
  
  # ensure full tracebacks are available and no help messages appear in test mode
  os.environ['NUMBA_DEVELOPER_MODE'] = '1'
  
  
  if __name__ == "__main__":
      runpy.run_module('numba.runtests', run_name='__main__')
  
new_contents: #!/usr/bin/env python
  import runpy
  import os
  
  if bool(os.environ.get('NUMBA_USE_TYPEGUARD')):
      # The typeguard import hook must be installed prior to importing numba.
      # Therefore, this cannot be part of the numba package.
      from typeguard.importhook import install_import_hook
      install_import_hook(packages=['numba'])
  
  # ensure full tracebacks are available and no help messages appear in test mode
  os.environ['NUMBA_DEVELOPER_MODE'] = '1'
  
  
  if __name__ == "__main__":
      runpy.run_module('numba.runtests', run_name='__main__')
  
subject: Add typeguard to runtests.py