Fixes to test cases
Simplify builtins stub

Remove the void return type so that more test cases pass.
Remvoe test cases that are no longer relevant
Improve docstrings and comments
Translate semantic analysis tests to new syntax
Add empty stub for typing
Update semantic analysis error test cases

Switch to new syntax.
Fix test case expected outputs

Pretty printed repr of AssignmentStmt was out of date in many test
cases.
Update test case
Fix semantic analysis of None types
Fix test cases
Do not dump 'typing' module in test cases
Analyse types in assignments
Add dummy typing.Undefined to test stubs

This is good enough for semantic analysis.
Analyse Any types
Fix test case
Add type annotations to builtins test stubs
Fix test case
Skip a test case that uses overloads
Fix test case