Guards are confusing.

The tests fail. Should they fail? Guards aren't doing the things that I'd
expect them to.
Syntax isn't Pythonic. Also, suchthat?

monte.lexer.ParseError:
                match n ? (n < 3) { return 0 }

               ^^^^^^^^^^^^^^^^
Parse error at line 20, column 15: Indented blocks only allowed in statement
positions.

Monte-for-wizards.txt strongly suggests that that's the correct syntax,
though.
TIL about brackets
Comment on what not to do
Handle switches correctly and add tests

test_switch.mt shows examples of the valid syntax for them.