Imagine you had this :
File A
File B
In File A, you declare a global variable, and import File B.
If you try to use that global variable in File B, you will probably get a compile error, since File B doesn't know anything about File A and its variables.
However, if you really felt the need to have globals everywhere, you could create a File C, put your global declarations in it, and import File C in each of the other files.
One thing you shouldn't do, is have File A importing File B, and File B importing File A. This creates the "Duplicate Identifier" compile errors.
If you find you need to do that then your design is flawed, and you should try to modify the code so that you don't need to import one of them.
File A
File B
In File A, you declare a global variable, and import File B.
If you try to use that global variable in File B, you will probably get a compile error, since File B doesn't know anything about File A and its variables.
However, if you really felt the need to have globals everywhere, you could create a File C, put your global declarations in it, and import File C in each of the other files.
One thing you shouldn't do, is have File A importing File B, and File B importing File A. This creates the "Duplicate Identifier" compile errors.
If you find you need to do that then your design is flawed, and you should try to modify the code so that you don't need to import one of them.