old_contents: #!/usr/bin/env python
  import os
  
  import yaml
  
  def load_config(yaml_filename):
      with open(yaml_filename, "r") as f:
          settings = yaml.load(f)
      return settings
  
  
  def get_tooltips(settings):
      tooltip_columns = settings['tooltip-columns']
      return [(column, '@' + column) for column in tooltip_columns]
  
new_contents: #!/usr/bin/env python
  import os
  
  import yaml
  
  def load_config(yaml_filename):
      with open(yaml_filename, "r") as f:
          settings = yaml.safe_load(f)
      return settings
  
  
  def get_tooltips(settings):
      tooltip_columns = settings['tooltip-columns']
      return [(column, '@' + column) for column in tooltip_columns]
  
subject: Update config.py to use yaml.safe_load()