Functions that return Enums?
The enum doesn't contain the code. The function is an ordinary function that happens to return a value of type enum status_code.

You don't normally see this syntax, because most programmers would also create a typedef for the enum status_code and use that to declare the type of the function's return value.

For example:

typedef enum status_code status_code_t;

status_code_t eeprom_emulator_init (void)
{
    ...