```
public interface AggregateFunctionManager
```
Manager class that it keeps a registry of AggregateFunction instances.

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Collection<AggregateFunction>`	`getAllFunctions()`	Get all the aggregate functions registered.
`AggregateFunction`	`getFunctionByType(AggregateFunctionType type)`	Get an aggregate function by its type.
`void`	`registerFunction(AggregateFunction function)`	Register an aggregate function.

getAllFunctions
```
Collection<AggregateFunction> getAllFunctions()
```
Get all the aggregate functions registered.

AggregateFunction getFunctionByType(AggregateFunctionType type)

Get an aggregate function by its type.

void registerFunction(AggregateFunction function)

Register an aggregate function.

Interface AggregateFunctionManager