[...]
stays ordered across deletions" part of the ruling is true in CPython 3.6.I don't know what guidance to give Eric, because I don't know what other implementations do nor whether Eric cares about being compatible with those. IIUC micropython does not guarantee this currently, but I don't know if they claim Python 3.6 compatibility -- in fact I can't find any document that specifies the Python version they're compatible with more precisely than "Python 3".
with, yield from, etc., and additionally async/await keywords from Python 3.5). The following core datatypes are provided: str (including basic Unicode support), bytes, bytearray, tuple, list, dict, set, frozenset, array.array, collections.namedtuple, classes and instances. Builtin modules include sys, time, and struct, etc. Select ports have support for _thread module (multithreading). Note that only a subset of Python 3 functionality is implemented for the data types and modules.