Add Sphinx docs
Implement type checking raise from
New test cases for raise from type checking
Cast super_type from Instance down to Type
Add more raise from statement test cases
Remove unused class in fixtures/exception.py
Semantic analyze from_expr of RaiseStmt
Add raise from type checking
Added semanal error message for assignment to empty tuple
Add type_check_raise() function and remove duplicate code
Change type to Node
Merge pull request #463 from yczhu/raise-from

Implement raise from type checking
Renamed identically named tests
Added tests for assignments from/to (nested) lists
Fixed style issues
Added tests for string interpolation
Added type checking for string interpolation
Add test for unsupported placeholders in string interpolation
Fixed handling of unsupported placeholders in string interpolation
Added tests for complex conversion specifiers (everything except mapping keys)