pxt-blockly has a few mechanisms for types (e.g. the shape of holes are determined based on those types), however, that might not be suitable for what we need. I'm assuming that however, this would be easy to implement.
will be tricky when using variables. I think it should be fine to throw an error when the types don't match in those cases. we want them to learn by doing.
another option is to estimate variable types at each line by tracing the variable
pxt-blockly has a few mechanisms for types (e.g. the shape of holes are determined based on those types), however, that might not be suitable for what we need. I'm assuming that however, this would be easy to implement.