Shortest code to generate a full mesh of elements
If I get it correctly, the shortest way that I can think of is by using itertools.combinations. Basically, you want all unique combinations, so:

from itertools import combinations

def mesh(L):
    return ["-&gt;".join(map(str, comb)) for comb in combinations(L, 2)]


Which will return:

['1-&gt;2', '1-&gt;3', '2-&gt;3']


For: mesh([1, 2, 3])

If you then want to print them as above, just:

for x in mesh([1, 2, 3]):
    print(x)