def format_direction(direction):
    """
    Examples
    --------
    >>> format_direction('ra')
    'ra'
    >>> format_direction('el')
    'alat'
    >>> format_direction('az')
    'alon'
    """
    lowerdir = direction.lower()
    if lowerdir == 'el':
        return 'alat'
    elif lowerdir == 'az':
        return 'alon'
    return direction