Feature request: enable global nesting by group

[aborruso]

Hi,
I would like to apply to this input

a,b,c
1,lorem,ips
1,rem,ips
2,cio,ran
2,sop,du

something like

mlr --csv nest -g a --nested-fs ";" input.csv

to get

a,b,c
1,lorem;rem,ips;ips
2,cio;sop,ran;du

And if it were possible to have the option to have uniq nested values:

mlr --csv nest -g a --nested-fs ";" --uniq input.csv

to get

a,b,c
1,lorem;rem,ips
2,cio;sop,ran;du

Thank you