str = "Hello"

for s in str:
    print(s)	# H	e	l	l	o

for t in range(5):
    print(t)

i = 0

while i < len(str):
    print(str[i])
    i+=1

========================
Iterator:
=========
==> an object
which enables the traversing on the collection like: list, tuple, dictionary etc.
only one element at time.
==> to implement the iterator:
	two methods:
		1) __iter__()
		2) __next__()

__iter__():
===========
	==> magical method
	==> return the iterator object
	==> which is point on the current element in collection
ex: [1,2,3,4,5]
__iter__() ==> current value = '1'
__next__() ==> next value = 2

__next__():
===========
	==> return the next element/item in the collection

Why the iterator object?
========================
to use the memory efficiently while handling the larger set of the data, iterator obect can use.

Iterating Statements (Iterable) Vs Iterator:
=============================================
for, while ==> from collection
	returning only one element at a time.

str = "Hello"

for s in str:
    print(s)	# H	e	l	l	o


iterator ==> can return stream of data

print(iter("Python"))
print(iter([1,2,3,4,5,6,7]))
print(iter({}))

# print(iter(100))

==================================

data = iter([1,3,5,7,9])

print(data)
print(data.__next__())
print(data.__next__())
print(data.__next__())
print(data.__next__())
print(data.__next__())
print(data.__next__())

How to Handle the exception while using the iterator:
=====================================================

d = iter(('abc','def','ghi','jkl','lmn'))

print(next(d))

while True:
    try:
        # the code which want to make execute normally even with exception.
        n = next(d)
        print(n)
    except StopIteration:
        break



==================================================
    
class myClass:
    def __init__(self, n):
        self.start = -1
        self.end = n

    def __iter__(self):
        return self

    def __next__(self):
        if self.start < self.end - 1:
            self.start += 2 # start = start + 2 1 3 5 7 9 11 13 15
            return self.start
        else:
            raise StopIteration
            
obj = myClass(5)   

while True:
    try:
        t = next(obj)
        print(t)
    except StopIteration:
        break