^^Python. Match statement. Structure pattern matching.

python/pep-0635/#patterns

#literal-patterns

the three singleton patterns:  None, False, True

match by identity (x is y in Python syntax) rather than equality (x==y)

Recall that literal patterns are not expressions, but directly denote a specific value.

From a pragmatic point of view,

• we want to allow using negative and even complex values as literal patterns, but they are not atomic literals (only unsigned real and imaginary numbers are).

E.g.  -3+4j  is syntactically an expression of the form

• BinOp(UnaryOp('-', 3), '+', 4j).

Since expressions are not part of patterns, we had to add explicit syntactic support for such values without having to resort to full expressions.