how can i not br defined?

[Skaperen]

a little script to print a horizontal rule with optional tab markers of an optional character (default '#') and an optional interval (default 8).

hr.py:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from __future__ import print_function
import fcntl,os,struct,termios
from os import environ as e
from sys import argv
try:
    h,w = struct.unpack('4H',fcntl.ioctl(1,termios.TIOCGWINSZ,struct.pack('4H',0,0,0,0)))[:2]
except:
    try:
        fd = os.open('/dev/tty',os.O_WRONLY)
        h,w = struct.unpack('4H',fcntl.ioctl(fd,termios.TIOCGWINSZ,struct.pack('4H',0,0,0,0)))[:2]
        os.close(fd)
    except:
        h,w = 1,80
b='-'
if 'b' in e: b=e['b']
r=[b]*w
if 'i' in e:
    try:
        i=int(e['i'])
    except:
        i=8
if 't' in e:
    t=e['t']
    if not t: t='#'
    for n in range(0,w,i):
        r[n]=t
if len(argv)>2:
    a=' '.join(argv[2:])
    for n in range(min(w,len(a))):
        r[n]=a[n]
print(''.join(r))

then this happens:

Output:
lt1/forums /home/forums 4> t='#' python3 hr.py
Traceback (most recent call last):
  File "hr.py", line 27, in <module>
    for n in range(0,w,i):
NameError: name 'i' is not defined
lt1/forums /home/forums 5>

either line 21 or line 23 should define variable "i" in local name space, before control reaches line 27, right? or am i missing something? how can the flow of control avoid both line 21 and line 23?