iterators | Python Fiddle

def firstn(n):
    num = 0
    while num<n :
    	yield num
        num += 1

class FirstN(object): 
   
    
	class Iterator(object) : 
		def __init__ (self,start,n) :
			self.max = n
			self.start = start
		def next(self) :
			if self.start >= self.max: raise StopIteration
			current = self.start
			self.start += 1
			return current
    
	def __init__ (self,start,n) :
		self.min = start
		self.max = n+start
        
	def __str__(self):
		return "Numbers from "+str(self.min)+ " to " + str(self.max-1) 
    
	def __iter__(self) : 
		return self.Iterator(self.min,self.max)
    
	def __getitem__(self,idx):return str(self.min+idx)
    
	@property
	def ffrom(self):
		return self.min
    
	@ffrom.setter
	def ffrom(self,value):
		self.min=value
        
	def get_tto(self):
		return self.max
    
	def set_tto(self,value):
		self.max=value
        
        
def sum2(i):
  it = i.__iter__()
  sv = 0
  try:
    while True:
        val = it.next()
        sv += val
  except StopIteration:
    print("Iteration done.")
        
  return sv

fn = FirstN(30,100)
fn.ffrom = 50
fn.fto = 150
print(fn.ffrom)
print(fn.fto)
print(fn[30])

#print(FirstN(100))

print(sum2(fn))

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