code: public function isPossibleType(AbstractType $abstractType, ObjectType $possibleType)
      {
          if ($abstractType instanceof InterfaceType) {
              return $possibleType->implementsInterface($abstractType);
          }
  
          /** @var UnionType $abstractType */
          return $abstractType->isPossibleType($possibleType);
      }
docs: Returns true if object type is concrete type of given abstract type
  (implementation for interfaces and members of union type for unions)
  
  @return bool
  
  @api