'ABCD' から [(0, 'A'), (1, 'B'), (2, 'C'), (3, 'D')] を作りたい。

gistfile1.py

s = 'ABCD'

# 1
i = 0
result = []

while True:
  if i >= len(s):
    break
  result.append((i, s[i]))
  i += 1

# 2
result = []

for x in range(len(s)):
  result.append((x, s[x]))

# 3
[(x, s[x]) for x in range(len(s))]

# 4
import itertools
list(zip(itertools.count(), s))

# 5, 忘れてた
list(enumerate(s))