old_contents: __version__ = '0.2.1'
  update_files = ['README.md', 'src/main.f90']
  
new_contents: __version__ = '0.2.1'
  update_files = ['README.md',
                  'src/pchk.f90',
                  'src/learn.f90', 'src/learn_command_line.f90',
                  'src/sample.f90', 'src/sample_command_line.f90',
                  'src/eval.f90', 'src/eval_command_line.f90']
  
subject: update list of files in version.py