python iterator

s = 'hello'
s_iter = iter(s) #Changes the string to an iterator
print(next(s_iter)) #Will print h
print(next(s_iter)) #Will print e
print(next(s_iter)) #Will print l
print(next(s_iter)) #Will print l
print(next(s_iter)) #will print o

pies = ["cherry", "apple", "pumpkin", "pecan"]

iterator = iter(pies)

print(next(iterator))
#prints "cherry" because it's the current one being iterated over

class PowTwo:
    """Class to implement an iterator
    of powers of two"""

    def __init__(self, max=0):
        self.max = max

    def __iter__(self):
        self.n = 0
        return self

    def __next__(self):
        if self.n <= self.max:
            result = 2 ** self.n
            self.n += 1
            return result
        else:
            raise StopIteration


# create an object
numbers = PowTwo(3)

# create an iterable from the object
i = iter(numbers)

# Using next to get to the next iterator element
print(next(i))
print(next(i))
print(next(i))
print(next(i))
print(next(i))

# define a list
my_list = [4, 7, 0, 3]

# get an iterator using iter()
my_iter = iter(my_list)

# iterate through it using next()

# Output: 4
print(next(my_iter))

# Output: 7
print(next(my_iter))

# next(obj) is same as obj.__next__()

# Output: 0
print(my_iter.__next__())

# Output: 3
print(my_iter.__next__())

# This will raise error, no items left
next(my_iter)

  import json

# some JSON:
x =  '{ "name":"John", "age":30, "city":"New 
  York"}'

# parse x:
y = json.loads(x)

# the result is a 
  Python dictionary:
print(y["age"])