def init(cls, typ, class2type):
        """
        Defines custom fields in the value factory so that the importer can find them
        @param typ
        @param class2type
        """
        field = typ.getField(cls.FIELD_NAME)
        class2type.put( StrStrHashMap , typ )
        typ.setComponentType( StrStrHashMap )
        typ.setImportExportHelper( StrStrHashMapSerializer(typ, field))
        typ.putValidator(field, Validator_object.get(1))
        typ.lock()
def flux_density(isa, subreg=[], ax=0):
    """plot flux density of NC/I7/ISA7 model
    Args:
      isa: Isa7/NC object
    """
    if subreg:
        if isinstance(subreg, list):
            sr = subreg
        else:
            sr = [subreg]
        elements = [e for s in sr for se in isa.get_subregion(s).elements()
                    for e in se]
    else:
        elements = [e for e in isa.elements]

    fluxd = np.array([np.linalg.norm(e.flux_density()) for e in elements])
    _contour(ax, f'Flux Density T', elements, fluxd)
    logger.info("Max flux dens %f", np.max(fluxd))