def should_sync_field(inclusion, selected, default=False):
    """
    Returns True if a field should be synced.

    inclusion: automatic|available|unsupported
    selected: True|False|None
    default: (default: False) True|False

    "automatic" inclusion always returns True:
    >>> should_sync_field("automatic", None, False)
    True
    >>> should_sync_field("automatic", True, False)
    True
    >>> should_sync_field("automatic", False, False)
    True
    >>> should_sync_field("automatic", None, True)
    True
    >>> should_sync_field("automatic", True, True)
    True
    >>> should_sync_field("automatic", False, True)
    True


    "unsupported" inclusion always returns False
    >>> should_sync_field("unsupported", None, False)
    False
    >>> should_sync_field("unsupported", True, False)
    False
    >>> should_sync_field("unsupported", False, False)
    False
    >>> should_sync_field("unsupported", None, True)
    False
    >>> should_sync_field("unsupported", True, True)
    False
    >>> should_sync_field("unsupported", False, True)
    False

    "available" inclusion uses the selected value when set
    >>> should_sync_field("available", True, False)
    True
    >>> should_sync_field("available", False, False)
    False
    >>> should_sync_field("available", True, True)
    True
    >>> should_sync_field("available", False, True)
    False

    "available" inclusion uses the default value when selected is None
    >>> should_sync_field("available", None, False)
    False
    >>> should_sync_field("available", None, True)
    True
    """
    if inclusion == 'automatic':
        return True
    if inclusion == 'unsupported':
        return False
    if selected is not None:
        return selected
    return default
