From that, I'd infer that surround a [b, c, d] means either a b c d a, or a b a c a d a, but definitely not b a c a d, where b and d are not "surrounded by as.
The standard library use words like intersperse or intercalate, which imply much better the idea of putting things "in between" other things, rather than all around.
Surrounding means to put stuff all around.
From that, I'd infer that
surround a [b, c, d]means eithera b c d a, ora b a c a d a, but definitely notb a c a d, wherebanddare not "surrounded byas.The standard library use words like
intersperseorintercalate, which imply much better the idea of putting things "in between" other things, rather than all around.