Unintuitive behavior for including metadata in @parameters/@variables begin end

[hstrey]

When declaring parameters using the new @mtkmodel DSL, one can either write:
@parameters tau A
or

@parameters begin
     tau
     A
end

Adding metadata to the parameters using begin end feels unintuitive:
Here is what is in the documentation (seems intuitive)
@parameters tau [tunable=true] A

I would have expected to write the following:

@parameters begin
          tau [tunable=true]
          A
end

but this does not work.

Instead, these two versions work:

@parameters begin
          tau, [tunable=true]
          A
end

@parameters begin
          tau
          [tunable=true]
          A
end

This syntax should at least be included in the documentation, but I would prefer the intuitive syntax if possible.

[cstjean]

The intuitive syntax (tau [tunable=true]) unfortunately does not parse as valid Julia code, so it is impossible to implement as a macro without changing Julia's parser.

The syntax with , is documented here.

Close?