def set_title(title=None, property_name=None, channel=None):
    """Set title for map.

    Parameters:
        title (str):
            If ``None``, try to set automatically from property (and channel)
            name(s). For no title, set to ''. Default is ``None``.
        property_str (str):
            Map property name. Default is ``None``.
        channel (str):
            Map channel name. Default is ``None``.
    Returns:
        str
    """
    if title is None:
        property_name = property_name if property_name is not None else ''
        channel = channel if channel is not None else ''
        title = ' '.join((property_name, channel))
        title = ' '.join(title.split('_')).strip()

    return title