mode values described for exec() and mode() pages do not match and are somewhat unclear
@sgougeon)
Reported by Samuel GOUGEON (mode = 0 :
help exec: default value
help mode: updated values of variables are displayed
mode = -1 : (OK)
mode = 1 :
help exec: each command line is displayed
help mode: = mode=3: each command line is displayed.
updated values are displayed.etc..
Descriptions for mode() and exec(..,mode) look near, but not clearly the same.