old_contents: #!/usr/bin/python
  
  import yaml
  
  def read_yaml(filename, readf=yaml.load):
      with open(filename, 'r') as f:
          return readf(f)
      
  def app_config(filename='app.secret.yml'):
      return read_yaml(filename)
  
  def store(yaml_obj, filename):
      with open(filename, 'wb') as f:
          yaml.dump(yaml_obj, f)
  
  def user_config(filename='user.secret.yml'):
      return read_yaml(filename)
  
  
new_contents: #!/usr/bin/python
  
  import yaml
  import sys
  
  def read_yaml(filename, readf=yaml.load):
      try:
          with open(filename, 'r') as f:
              return readf(f)
      except IOError:
          print("File '%s' not found." % filename)
          sys.exit(1)
  
  
  def app_config(filename='app.secret.yml'):
      return read_yaml(filename)
  
  def store(yaml_obj, filename):
      with open(filename, 'wb') as f:
          yaml.dump(yaml_obj, f)
  
  def user_config(filename='user.secret.yml'):
      return read_yaml(filename)
  
  
subject: add IOError catch