useInstancePart<InstancePartType extends BaseInstancePart<dynamic, MvvmInstance> >  method 
      
InstancePartType
useInstancePart<InstancePartType extends BaseInstancePart<dynamic, MvvmInstance> >({  
    
- int index = 0,
Returns initialized instance part for given type
index - index for this part
Implementation
InstancePartType useInstancePart<InstancePartType extends BaseInstancePart>({
  int index = 0,
}) {
  if (_parts[InstancePartType] == null) {
    throw IllegalStateException(
      message: 'Part $InstancePartType is not connected.',
    );
  }
  if (index < 0 || index >= _parts[InstancePartType]!.length) {
    throw IllegalArgumentException(
      message:
          'The index = $index value must be non-negative and less than count of parts of $InstancePartType.',
    );
  }
  return _parts[InstancePartType]![index] as InstancePartType;
}