How to use/convert sed to Python?

Any idea to convert the given line below into Python?

sed 's+forwarding_link+'$link'+g' first.html > index2.html

with open('first.html') as infile:
    data = infile.read()

data = data.replace('forwarding_link', link)

with open('index2.html', 'w') as outfile:
    outfile.write(data)

This might useful