The problem:
Currently, built-in functions are represented by the catch-all block because Blockly doesn't understand that there are such things as builtins in Python.
The requirements:
The builtin functions of Python need to be defined so they're treated properly by py2blocks. Also, given that py2blocks is part of the tooling for the Invent framework, we should also include blocks that represent the Invent API.
The solution:
TBD