docs: def get_auth_error_message(self):
          ''' create an informative error message if there is an issue authenticating'''
          errors = ["Authentication error retrieving ec2 inventory."]
          if None in [os.environ.get('AWS_ACCESS_KEY_ID'), os.environ.get('AWS_SECRET_ACCESS_KEY')]:
              errors.append(' - No AWS_ACCESS_KEY_ID or AWS_SECRET_ACCESS_KEY environment vars found')
          else:
              errors.append(' - AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment vars found but may not be correct')
  
          boto_paths = ['/etc/boto.cfg', '~/.boto', '~/.aws/credentials']
          boto_config_found = list(p for p in boto_paths if os.path.isfile(os.path.expanduser(p)))
          if len(boto_config_found) > 0:
              errors.append(" - Boto configs found at '%s', but the credentials contained may not be correct" % ', '.join(boto_config_found))
          else:
              errors.append(" - No Boto config found at any expected location '%s'" % ', '.join(boto_paths))
  
          return '\n'.join(errors)