def make_cmd(entity, extras=None):
    """ Convert YAML entry into commandline call

    Args:
        entity (dict): The serialzied represntation of command
        extras (dict): format values to insert into arg calls

    Returns:
        str: The formatted string

    Example:
        >>> make_cmd({"cmd": "echo", "args": "hello"})
        'echo hello'
    """
    args = ' '.join('{} {}'.format(x, y.format(**extras) if y is not None else '') for z in entity.get('args', []) for x, y in z.items())
    return '{cmd} {args}'.format(args=args, cmd=entity['cmd']) if 'cmd' in entity else ''