from itertools import chain

string = 'Toronto'
chain(string)

<itertools.chain at 0x108ed2ba8>

chars = chain(string)

type(chars)

itertools.chain

chars

<itertools.chain at 0x108ed2b70>

for c in chars:
    print(c)

T
o
r
o
n
t
o

for c in chars:
    print(c)

# Since the iteration is finished, you can't get the characters one more time