```nvec ← {sepr} ##.ltov lvec                  ⍝ Lines to nested vector.
lvec ← {sepr} ##.vtol nvec                  ⍝ Nested vector to lines.

Each function is an approximate equivalent of the xutils AP function of the same
name. [ltov] and [vtol] convert between nested vectors and →Line_vectors←.

Note that [vtol] appends a [sepr] character after each item of the argument, in-
cluding the last. This means that, in general: lvec ≢ vtol ltov lvec.

More  generally, [sepr] may be a vector of separators of any shape or depth, see
examples below.

Examples:

nl←⎕ucs 13                              ⍝ newline.

lvec←'fooling around', nl, 'with barrels', nl, 'in alleys'

lvec                                    ⍝ line vector.
fooling around
with barrels
in alleys

ltov lvec                               ⍝ nested vector.
┌──────────────┬────────────┬─────────┐
│fooling around│with barrels│in alleys│
└──────────────┴────────────┴─────────┘

nl=lvec                                 ⍝ note, no trailing nl:
0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0

nl=vtol ltov lvec                       ⍝ note extra nl:
0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1

(nl,' ')ltov lvec                       ⍝ split at newline or blank.
┌───────┬──────┬────┬───────┬──┬──────┐
│fooling│around│with│barrels│in│alleys│
└───────┴──────┴────┴───────┴──┴──────┘

0 ltov 1 2 3 0 4 5 6 0 7 8 9            ⍝ split numeric vector.
┌─────┬─────┬─────┐
│1 2 3│4 5 6│7 8 9│
└─────┴─────┴─────┘

⊢ rainbow ← 'red' 'and' 'yellow' ',' 'pink' 'and' 'green'
┌───┬───┬──────┬─┬────┬───┬─────┐
│red│and│yellow│,│pink│and│green│
└───┴───┴──────┴─┴────┴───┴─────┘

(⊂'and')ltov rainbow                    ⍝ split nested vector
┌─────┬───────────────┬───────┐
│┌───┐│┌──────┬─┬────┐│┌─────┐│
││red│││yellow│,│pink│││green││
│└───┘│└──────┴─┴────┘│└─────┘│
└─────┴───────────────┴───────┘

'and' ',' ltov rainbow
┌─────┬────────┬──────┬───────┐
│┌───┐│┌──────┐│┌────┐│┌─────┐│
││red│││yellow│││pink│││green││
│└───┘│└──────┘│└────┘│└─────┘│
└─────┴────────┴──────┴───────┘