LOG = logging.getLogger()
+
+def flatten_config_list(content, section=''):
+ """ Flatten YAML configuration lists that contain include sections
+ which are lists themselves.
+ """
+ if not content:
+ return []
+
+ if not isinstance(content, list):
+ raise UsageError(f"List expected in section '{section}'.")
+
+ output = []
+ for ele in content:
+ if isinstance(ele, list):
+ output.extend(flatten_config_list(ele, section))
+ else:
+ output.append(ele)
+
+ return output
+
+
class Configuration:
""" Load and manage the project configuration.