def find_ws_name(wb, name):
    """Busca una hoja en un workbook sin importar mayúsculas/minúsculas."""
    if isinstance(wb, string_types):
        # FIXME: importar o borrar segun corresponda
        wb = load_workbook(wb, read_only=True, data_only=True)

    for sheetname in wb.sheetnames:
        if sheetname.lower() == name.lower():
            return sheetname

    raise Exception("No existe la hoja {}".format(name))