def METHOD_NAME(crs):
    if crs is None:
        return
    if isinstance(crs, str):
        try:
            crs_set.add(geometry.CRS(crs))
        except geometry.CRSError:
            warnings.warn(f"Failed to parse CRS: {crs}")
    elif isinstance(crs, geometry.CRS):
        # support current bad behaviour of injecting CRS directly into
        # attributes in example notebooks
        crs_set.add(crs)
    else:
        warnings.warn(f"Ignoring crs attribute of type: {type(crs)}")