[O] suppress leading ":" in org-babel output

[Jeremie Juste]

Hello,

I recall seeing this thread on the mailing list but I cannot find it
back.

I would like to suppress the first line leading ":" in the following output


#+NAME:mean_purchase_per_shopping_trip
#+BEGIN_SRC R :var x=6 :results output :session *R*
a <-sprintf("%.2f",12.234324)
cat(a,sep="\n")
#+END_SRC

#+RESULTS: mean_purchase_per_shopping_trip
: 
: 12.23


Best regards,
Jeremie

Org mode version 9.2.1 (9.2.1-8-g1b1797-elpaplus @
/home/djj/.emacs.d/elpa/org-plus-contrib-20190211/)
GNU Emacs 26.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.11) of 
2019-05-16