python string search replace

Question

SSViewer::set_theme(\'bullsorbit\'); 

this my string. I want search in string \"SSViewer::set_theme(\'bullsorbit\'); \" and replace

Answer 1

st = "SSViewer::set_theme('"
for line in open("file.txt"):
    line=line.strip()
    if st in line:
        a = line[ :line.index(st)+len(st)]
        b = line [line.index(st)+len(st): ]
        i = b.index("')")
        b = b[i:]
        print a + "newword" + b