Load step from yaml file
    Args:
        filename: a target or step.yaml filename

def load(filename):
    """
    Load step from yaml file
    Args:
        filename: a target or step.yaml filename
    """
    yaml_filename = os.path.join(os.path.dirname(filename), 'step.yaml')
    with open(yaml_filename) as f:
        return yaml.load(f)