:param filename: relative filename with .vhdl or .v

    :return: add_fileset_file command string

def tcl_add_fileset_file(filename: str):
    """
    :param filename: relative filename with .vhdl or .v

    :return: add_fileset_file command string
    """
    if filename.endswith(".vhd"):
        t = "VHDL"
    elif filename.endswith(".v") or filename.endswith(".sv"):
        t = "VERILOG"
    else:
        raise NotImplementedError(
            "Can not resolve type of file by extension", filename)
    name = basename(filename)

    return "add_fileset_file %s %s PATH %s" % (name, t, filename)