samples/c_interface/*:
Replace left over references to the old c_header_code pragma.
Replace some uses of '__' as a module qualifier.
Replace tabs with spaces.
Add some missing words.
Estimatd hours taken: 0.5
Branches: main
samples/*.m:
Use '.' as the module qualifier instead of '__'.
Use the new foreign language interface.
Fix minor formatting issues.
Use state variables for passing the I/O state.
