/**
* Group A Sequence based upon the result of $fnMapValueToGroup($value, $key) and return the result as a Sequence
*
* @param callable $fnMapValueToGroup($value, $key) -- return the field name to group the values under.
* @param array $keys - used to initialize the keys for the resulting groups
* @return static
*/
public function groupByInitWithKeys($fnMapValueToGroup, $keys)
{
return static::make(IterationTraits::groupByInitWithKeys($this, $fnMapValueToGroup, $keys));
}
