* [Flow] Function predicate declaration
The accepted syntax for function declarations is extended to allow
the following predicate declaration:
FunctionReturnType :=
Type
Predicate
Type Predicate
Predicate :=
%checks
%checks ( ConditionalExpression )
* [Flow] Minor tweaks and more examples to function predicates
* [Flow] Clean-up and better message for function predicates
* [Flow] Adding abstract function predicate example
* [Flow] Rearranging the `predicate` field to ease babel generator.
e049ec3456