This is what you want: (source)
re.finditer(pattern, string[, flags])Return an iterator yielding MatchObject instances over all
non-overlapping matches for the RE pattern in string. The string is
scanned left-to-right, and matches are returned in the order found. Empty
matches are included in the result unless they touch the beginning of
another match.
You can then get the start and end positions from the MatchObjects.
e.g.
[(m.start(0), m.end(0)) for m in re.finditer(pattern, string)]