How would you (as an python expert) make this code more efficient/simple

[Gribouillis]

A more flexible version with itertools

import itertools as itt

def sandwich(chain, sep):
    yield from sep
    for c in chain:
        yield from c
        yield from sep

def tablerows(r, c):        
    top = ''.join(sandwich((sandwich('-' * n, ' ') for n in c), '+'))
    mid = ''.join(sandwich((' ' * (2 * n + 1) for n in c), '|'))
    return sandwich((itt.repeat(mid, k) for k in r), (top,))

a = (3, 2, 4)
b = (2, 4, 3, 1)

for r in tablerows(a, b):
    print(r)

Output:
+ - - + - - - - + - - - + - +
|     |         |       |   |
|     |         |       |   |
|     |         |       |   |
+ - - + - - - - + - - - + - +
|     |         |       |   |
|     |         |       |   |
+ - - + - - - - + - - - + - +
|     |         |       |   |
|     |         |       |   |
|     |         |       |   |
|     |         |       |   |
+ - - + - - - - + - - - + - +