julia> module Foo
           a = 5
           export a
       end
Main.Foo

julia> using Foo
ERROR: ArgumentError: Package Foo not found in current path, maybe you meant `import/using .Foo`. Otherwise, run `import Pkg; Pkg.add("Foo")` to install the Foo package.
Stacktrace:
 [1] require(into::Module, mod::Symbol)
   @ Base ./REPL[1]:19