Question

def escape_html(s):
    for (i, o) in (("&","&amp;"),(">", "&gt;"),("<", "&lt"),('"', "&quot;")):
        s = s.replace(i , o)
    return s

I haven’t seen something like this before.

What does the first line of the for loop mean?

In general, what does the loop do and how does it do it?

Note: s is a string

Please try to explain the full iterative process.

Answer 1

for each pair of items i and o in the sequence of pairs (("&","&amp;"),(">", "&gt;"),("<", "&lt"),('"', "&quot;")), it replaces each instance of i with o in the string s.