Error in the @by example in the documentation

[sbacelar]

The example of @by in the documentation gives an error: ERROR: ArgumentError: column :x in returned data frame is not equal to grouping key :x Maybe it was better :y_sum = sum(:y)

using DataFrames
using DataFramesMeta

df = DataFrame(x = [1, 1, 2, 2], y = [1, 2, 101, 102]);
@by df :x begin
           :x = sum(:y)
           end