src/Set.php
public function diff(Set $set): Set
    {
        return $this->table->diff($set->table)->keys();
    }
public function diff(Set $set): Set
    {
        return $this->table->diff($set->table)->keys();
    }
public function diff ( Set $ set ) : Set { return $ this -> table -> diff ( $ set -> table ) -> keys ( ) ; }
Creates a new set using values from this set that aren't in another set.

Formally: A \ B = {x ∈ A | x ∉ B}

@param Set $set

@return Set
Creates a new set using values from this set that aren t in another set .