Matt Gonzalez

In my opinion: > Are we OK to have only one :variable_name column (does anyone need multiple variable name columns in practice?) Yes-- I would prefer to keep it simple....

I agree that a special case for `Not()` is necessary. This request is similar to #283, which proposes—among other changes—the use of `@select df Not(:a)` as opposed to the current...

Sure-- I'll check this out @pdeffebach

@pdeffebach Do you have any examples in mind for applications of the `@bycol` flag? Are you looking for something like: ``` @chain df begin transform(@bycol r"x" .=> mean) end ```...

Got it-- I'll start working!