The type of the `ix_data` binding withing the solitaire! macro expansion
is explicitly annotated with its type, which comes from the macro's
pattern binding `$kind`. However, this type annotation is entirely
optional, since `ix_data` is passed in as an argument to `$fn`, whose
type forecs `ix_data` anyway, and rust will happily infer that from the
application. So we remove the explicit annotation which makes the entry
point macro easier to use.
commit-id:d428306c
f60acc59ab