title: How-to import constants in many files
body: <p>I have a package containing many modules. Each module uses constants that I have defined independently in each file.
  However, all these constants have to be constistent with each other. So I try to define them in a single file and import it in each file. When I run it I have errors for constants not found.</p>
  
  <p>Is their a clean way to have a single file imported by many others and containing constants ?</p>
  
  <p>Thanks for your help</p>