# module `concrete.fhe.extensions.table`
Declaration of `LookupTable` class.
---
## class `LookupTable`
LookupTable class, to provide a way to do direct table lookups.
### method `__init__`
```python
__init__(table: Any)
```
---
### method `apply`
```python
apply(
key: Union[int, integer, bool_, ndarray],
table: ndarray
) → Union[int, integer, ndarray]
```
Apply lookup table.
**Args:**
key (Union[int, np.integer, np.bool_, np.ndarray]): lookup key
table (np.ndarray): lookup table
**Returns:**
Union[int, np.integer, np.ndarray]: lookup result
**Raises:**
ValueError: if `table` cannot be looked up with `key`