Searching a window of text in Python

s = "state"
f = open("machiavelli_pg1232.txt")
lines = f.readlines()
numlines = len(lines)

# PASS 1: Search the text in "windows" of 5 lines
# If the keywords are both there (this condition you can adapt)
# MARK the line numbers of the window (by adding the line numbers to the "hits" set)
hits = set()
for n in range(0, numlines-5):
    block = ""
    for line in lines[n:n+5]:
        block += line

    if "state" in block and "work" in block:
        for n in range(n, n+5):
            hits.add(n)

# PASS 2: Display the linenumbers that are in hits
lastline = 0
for n in range(0, numlines):
    if n in hits:
        line = lines[n].strip()
        if n > lastline + 1:
            print "========================="
        # print n, line
        print line.replace("state", "STATE").replace("work", "WORK")
        lastline = n

# for line in f:
#     if "state" in line and "work" in line:
#         print line