[NTG-context] Positioning an arrow between two values (Metapost)

Hi, I went from PSTricks to Metapost (Metafun) gradually. For positioning arrows between two values in an array of variations, I used a command like this \ ncline {A}{B}, which avoids fumbling. Can we do the same with Metapost ? The idea would be to convert the value into a path or an image, much like in the code below. \starttext \startMPcode u:=1cm ; path p, q ; p=fullsquare scaled u ; q=fullsquare scaled u shifted (4u,-2u) ; draw p ; draw q ; drawarrow center p--center q ; label(btex $5$ etex,center p) ; label(btex $-2 $ etex,center q) ; \stopMPcode \stoptext Best regards, Fabrice