Footnotes

...^3.1^3.1: The interpreter should really distinguish between user-defined classes implementing sequences, mappings or numbers, but currently it doesn't — hence this strange exception.
...^4.1^4.1: If the code block contains exec statement or the construct from ... import *, the semantics of names not explicitly mentioned in a global statement change subtly: name lookup first searches the local name space, then the global one, then the built-in one.
...^5.1^5.1: This is expensive since it requires sorting the keys first, but about the only sensible definition. An earlier version of Python compared dictionaries by identity only, but this caused surprises because people expected to be able to test a dictionary for emptiness by comparing it to {}.
...^5.2^5.2: The latter restriction is sometimes a nuisance.
... loop.^6.1^6.1: Except that it may currently occur within an except clause.
...^7.1^7.1: Currently this is not checked; instead, def f(a=1,b) is interpreted as def f(a=1,b=None).