old_contents: import os
  
  # expandvars expands e.g. $HOME
  DATA_DIR = os.path.expandvars('$HOME/stormtracks/data')
  OUTPUT_DIR = os.path.expandvars('$HOME/stormtracks/output')
  
new_contents: import os
  
  # expandvars expands e.g. $HOME
  DATA_DIR = os.path.expandvars('$HOME/stormtracks/data')
  OUTPUT_DIR = os.path.expandvars('$HOME/stormtracks/output')
  
  C20_FULL_DATA_DIR = os.path.join(DATA_DIR, 'c20_full')
  C20_MEAN_DATA_DIR = os.path.join(DATA_DIR, 'c20_mean')
  IBTRACS_DATA_DIR = os.path.join(DATA_DIR, 'ibtracs')
  
subject: Add new default settings.