How do I indicate that an Array is an Array?

The code below is a script intended to yield a two dimensional array. However whenever I run the code It cannot splice the arrays because it thinks that thy are objects. I've written the same code in C# and Boo but get the same error.

 import UnityEngine
 
 class Chunk_assignment (MonoBehaviour):
         count = 20
     times = 20
     def Start ():
         world = []
         line_template = []
         for y in range(0,127):
         #sets up a template that is 128 long and consists entirely of '~'#
             line_template.Add('~')
         for x in range(0,127):
         #creates an arrray, the world, that is 128 lines of the template just created#
             world.Add(line_template)
         for x in range(count):
         #Creates 20 'X's at random inside the world#
             world[Random.Range(1,len(world)-2)][Random.Range(1,len(world[0])-2)] = 'X'
         for x in range(times):
             #makes the first and last lines empty to prevent errors when expanding#
             world[0] = line_template
             world[len(world)-1] = line_template
             for x in range(0,len(world)-1):
                 world[0].Add('~')
                 world[len(world)-1].Add('~')
             linenum = 0
             for line in world:
                 newline = ['~']
                 #cleans up the vartical edges (makes all entries '~')#
                 for tilenum in range(1,len(world[linenum])-2):
                     newline.Add(world[linenum][tilenum])
                 world[linenum] = newline.Add('~')
                 linenum += 1
             linenum = 0
             for line in world:
                 tilenum = 0
                 for tile in line:
                     #planned code, currently not needed#
 #                    if tile == 'X' == world[Linenum+1][tilenum+1] == world[Linenum+1][tilenum] == world[Linenum+1][tilenum-1] == world[Linenum][tilenum+1] == world[Linenum][tilenum-1] == world[Linenum-1][tilenum+1] == world[Linenum-1][tilenum] == world[Linenum-1][tilenum-1]:
 #                        world[linenum][tilenum] = 'x'
                     if tile == 'X':
                         #for each X creates one new X near (or in) it#
                         world[linenum+Random.Range(-1,1)][tilenum+Random.Range(-1,1)] = 'X'
                     tilenum += 1
                 linenum += 1
     def Update ():
         pass