'continue' the 'for' loop to the previous element

Here when the corresponding value of i is equal to c the element will change to your request and go back one step, reprinting b and abc, and finally d:

foo = ["a", "b", "c", "d"]
i = 0
while i < len(foo):
    if foo[i] == "c":
        foo[i] = "abc"
        i -= 1
        continue
    print(foo[i])
    i += 1

In a for loop you cannot change the iterator. Use a while loop instead:

foo = ["a", "b", "c", "d"]
i = 0
while i < len(foo):
    if foo[i] == "c":
        foo[foo.index(foo[i])] = "abc"
        i -= 1
        continue
    print(foo[i])
    i += 1    

I wanted to use for so I created the code myself. I didn't want to modify my original list so I made a copy of my original list

foo = ["a", "b", "c", "d"]
foobar = foo.copy()

for bar in foobar:
    if bar == "c":
        foobar[foobar.index(bar)] = "abc"
        foo[foo.index(bar)] = "abc"
        del foobar[foobar.index("abc")+1:]
        foobar += foo[foo.index("abc")-1:]
        continue
    print(bar)

It prints as expected:

a
b
b
abc
d

And my original list also is now:

['a', 'b', 'abc', 'd']

import collections
left, right = -1,1
foo = collections.deque(["a", "b", "c", "d"])
end = foo[-1]
while foo[0] != end:
    if foo[0] == 'c':
        foo[0] = 'abc'
        foo.rotate(right)
    else:
        print(foo[0])
        foo.rotate(left)
print(foo[0])