def get_fqn_valid_for_module_dict_key(fqn: str) -> str:
    """
    Modifies `fqn`(fully qualified name) to make it a valid key to a ModuleDict.
    """
    if fqn == "":
        fqn = " "
    return fqn.replace(".", ":")

    Modifies `fqn`(fully qualified name) to make it a valid key to a ModuleDict.
    
intel_extension_for_pytorch/quantization/_utils.py