code: def load_yaml_file(filename):
      
      try:
          with open(filename, 'r') as f:
              return yaml.safe_load(f)
      except IOError as e:
          raise ParserError('Error opening ' + filename + ': ' + e.message)
      except ValueError as e:
          raise ParserError('Error parsing processes in {}: {}'
                            .format(filename, e.message))
docs: Load a YAML file from disk, throw a ParserError on failure.