Fix a scoping bug, and add a test so it doesn't come back
Throw an error if an object cannot handle a binary operator
Allow int() constructor to be used in one- and two-argument forms, like Python
Add unary minus for integers
Make sure attribute access failure doesn't result in infinite recursion, by properly checking for class-level method presence
Tiny cleanups for error handling
Add super basic struct module to stdlib
Add very basic beginning to x86-64 assembler
Add simple 1-operand instructions
Add __str__ to assembler classes