@join on columns of the same name

[mcabbott]

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It would be neat if it wasn't necessary to repeat the name of the columns on which you are joining, when they are the same:

@join(foo, bar, _.joincolumn, _.joincolumn, {_.other, __.also})

Right now the macro seems to just go by the number of arguments, so omitting one tries to create a function for foo |> @join(bar, ... use, but perhaps it could look at what it gets before deciding?