How to use the yacman.load_yaml function in yacman

if config_to_load is not None:
                    pass
                    # TODO: Switch this message to a debug message using _LOGGER
                    self.debug("\nUsing custom config file: {}".format(config_to_load))
            else:
                # No custom config file specified. Check for default
                default_config = default_pipeline_config(sys.argv[0])
                if os.path.isfile(default_config):
                    config_to_load = default_config
                    self.debug("Using default pipeline config file: {}".
                          format(config_to_load))

        # Finally load the config we found.
        if config_to_load is not None:
            self.debug("\nLoading config file: {}\n".format(config_to_load))
            self.config = AttMapEcho(load_yaml(config_to_load))
        else:
            self.debug("No config file")
            self.config = None

def __init__(self, config_file=None, pm=None):
        # parse yaml into the project's attributes
        # self.add_entries(**config)
        super(NGSTk, self).__init__(
            None if config_file is None else load_yaml(config_file))

        # Keep a link to the pipeline manager, if one is provided.
        # if None is provided, instantiate "tools" and "parameters" with empty AttMaps
        # this allows the usage of the same code for a command with and without using a pipeline manager
        if pm is not None:
            self.pm = pm
            if hasattr(pm.config, "tools"):
                self.tools = self.pm.config.tools
            else:
                self.tools = AttMapEcho()
            if hasattr(pm.config, "parameters"):
                self.parameters = self.pm.config.parameters
            else:
                self.parameters = AttMapEcho()
        else:
            self.tools = AttMapEcho()

def _read_schema(schema):
    """
    Safely read schema from YAML-formatted file.

    :param str | Mapping schema: path to the schema file
        or schema in a dict form
    :return dict: read schema
    :raise TypeError: if the schema arg is neither a Mapping nor a file path
    """
    if isinstance(schema, str):
        return _load_yaml(schema)
    elif isinstance(schema, dict):
        return schema
    raise TypeError("schema has to be either a dict, URL to remote schema "
                    "or a path to an existing file")

def read_schema(schema):
    """
    Safely read schema from YAML-formatted file.

    :param str | Mapping schema: path to the schema file
        or schema in a dict form
    :return dict: read schema
    :raise TypeError: if the schema arg is neither a Mapping nor a file path
    """
    if isinstance(schema, str):
        return _load_yaml(schema)
    elif isinstance(schema, dict):
        return schema
    raise TypeError("schema has to be either a dict, URL to remote schema "
                    "or a path to an existing file")