diagonal maze

#!/usr/env python2
slant={
    ' ':' ',
    '+':'x',
    '|':'/',
    '-':'\\'
    }


def slantc(character):
    return slant[character]

class maze:
    def __init__(self,strin):
        self.string=strin
        self.makegrid(strin)

    def makegrid(self,strin):
        from pprint import pprint
        lines = strin.splitlines()
        yl = int(lines[0])
        lines = lines[1:yl+1]
        xl=len(lines)
        grid=[]
        for _ in range(yl*2-1): grid.append([' ']*(xl))
        l=0
        o=[]
        lastlines=[]
        for l in range(len(lines)):
            first = lines[l][0:l+1]
            lastlines.append(lines[l][l+1:xl]) #xl to cut any extra off
            z=xl-l-1
            f=len(first)
            for c in range(len(first)):
                n=first[c]
                grid[l+c][z+c]=n
        lastlines.reverse()
        startl=len(grid)
        derp=True
        for row in range(len(grid)): #sorry... #it_works on sizes of 1,2,4
            derp=not derp
            if derp:
                grid[row].pop()
        for l in range(len(lastlines)):
            line=[a for a in lastlines[l]]
            line.reverse()
            for c in range(len(line)):
                z=-l-1-c
                grid[z].append(' ')
                n=line[c]
                grid[z].append(n)
        self.grid=grid

    def __str__(self,removeplus=False):
        r=''
        first=True
        for row in self.grid:
            l=[slantc(a) for a in row]
            s=''.join(l)
            if not first: s='\r\n'+s
            first=False
            r=r+s
        return r

if __name__=="__main__":
    mazestr_hash="""11
#0123456789a
###########b
###########c
###########d
###########e
###########f
###########g
###########h
###########i
###########j
###########k"""
    mazestr1="""11
+-+-+-+-+-+
  |       |
+ +-+-+ + +
| |     | |
+ + + + + +
|   | |   |
+-+-+ +-+-+
|     |   |
+ + +-+ + +
| |     | |
+-+-+-+-+-+"""
    mazestr2="""16
+--+  +--+--+--+
      |     |  |
      |     |  |
+  +--+  +  +  +
      |  |  |  |
      |  |  |  |
+--+  +  +  +  +
|     |  |     |
|     |  |     |
+  +--+  +  +--+
|        |     |
|        |     |
+--+--+--+--+  +
|
|
+--+--+--+--+--+"""
    mazestr3="""17
+---+---+---+---+---+---+
                        |
                        |
                        |
+---+---+---+---+---+   +
                        |
                        |
                        |
+---+---+---+---+---+---+
|
|
|
+   +---+---+---+---+---+
|
|
|
+---+---+---+---+---+---+"""
    m=maze(mazestr1)
    print m