Packages, @INC and Namespace hierarchy

---

perl -V

@INC:
  C:/strawberry/test-perl/lib
  C:/strawberry/test-perl/site/lib
  C:\strawberry\perl\vendor\lib
  .

require Calc; - Calc.pm somewhere in @INC

require Math::Calc; - Math/Calc.pm somewhere in @INC

require Math::Calc::Clever; - Math/Calc/Clever.pm somewhere in @INC