#python

• d.get(k, default) is not d.get(k) or default
  2026-06-03

  The two forms answer different questions; "or default" fires on every falsy stored value, not on a missing key.

• x is None, not x == None (and NaN isn't equal to itself)
  2026-06-01

  In Python use is for the singletons and == for values — and remember that NaN never compares equal to itself.