v1.3.4 - fix return type for `merge` in README

v1.3.3 - refine types and docstrings

v1.3.2 - add py.typed and update typings, close #2

v1.3.1 - add Python 3.9 support classifier

v1.3.0 - support additive merging of `Counter` types

v1.2.1 - tidy docs and variable names

v1.2.0 - support both TYPESAFE_REPLACE and TYPESAFE_ADDITIVE merge st…

…rategies, fix #1

v1.1.1 - support `tuple` merging when using ADDITIVE strategy

v1.0.3 - minor perf improvements by limiting deepcopy

v1.0.2 - support three different merge strategies: (replace, additive…

…, typesafe)