Behavior Change: Added special-cased handling for __slots__ and __class_getitem__ in protocol matching logic.
Enhancement: Improved bidirectional type inference for lambdas with default argument values.
Enhancement: Improved heuristics for when constraint solver should prefer literals over non-literals when solving a TypeVar in the case of bidirectional inference when assigning to a callable type.
Enhancement: Added support for unpacking of tuples in type annotations (part of PEP 646).
Bug Fix: Fixed bug that resulted in false positive error when a Literal was used within a Python-2 style type annotation comment.
Enhancement: Updated typeshed stubs to the latest.
Bug Fix: Fixed bug in "x is None" type guard logic. It wasn't preserving conditional types if x was a TypeVar.
Bug Fix: Fixed bug that resulted in false positive error when a constrained TypeVar was checked against a particular constraint in an isinstance type guard.
Bug Fix: Fixed a bug in the logic for assignment-based type narrowing that resulted in the wrong narrowed type if the declared type of the destination expression contained a union and the source contained a TypeVar.