python script for changing line in a file in patch way

worker.py

srcFileName = r'file1.java'
dstFileName = r'file2.java'

srcFile = open(srcFileName,'r')
dstFile = open(dstFileName,'w')

def listToStr(alist):
    result ='';
    for a in alist:        
        result += ', %s' % a
    return result    

def processLine(line):
    try:
        indexFun = line.index('someFunction')
    except:
        return line

    indexLeftBracket = line.index('(')
    indexRightBracket = line.index(')')
    allArguments = line[indexLeftBracket+1:indexRightBracket]
    argumentList = allArguments.split(',')
    if len(argumentList) != 3:
        return line
    newLine = line[0:indexLeftBracket]+'('+argumentList[0]+', '+argumentList[1] + ', '+argumentList[1] +', '+argumentList[2] +');\n'
    return newLine
    

for line in srcFile.readlines():
    newLine = processLine(line)
    dstFile.write(newLine)

srcFile.close()
dstFile.close()