old_contents: class Algorithm:
  	"""
  	Algorithm Class
  
  	Base class for the page substitution algorithms.
  	"""
  	def __init__(self, input = []):
  		"""
  		Algorithm Constructor.
  
  		Parameters
  		----------
  		input : list
  			A list containing the the input page swap. 
  		"""
  		if not input: #If the list is empty throw an exception.
  			raise ValueError("The list must not be empty") #throws the exception.
  		self.blocks = input[0] #Store the page frames size.
  		self.pages = input[1:] #Store the pages to swap.
  		self.missingPages = self.blocks #Count the lack of pages.
  
  	def removeChuncks(self, list, start, stop):
  		"""
  		Remove a piece of a list.
  
  		Parameters
  		----------
  		list : list
  			The list to delete the elements
  		start : int
  			start point.
  		stop : int
  			stop point.
  		"""
  		del list[start:stop] #Delete range
  
  	def preparePageFrame(self):
  		"""
  		Prepare the page frames.
  
  		Returns
  		-------
  		list
  			The list with initialized Page frames
  		"""
  		pageFrame = [self.pages[x] for x in range(0, self.blocks)] #Create the page frame with elements passed by the user.
  		self.removeChuncks(self.pages, 0, self.blocks) #Remove part of the list that is on the page frame
  		return pageFrame #Return the list
  
new_contents: class Algorithm:
  	"""
  	Algorithm Class
  
  	Base class for the page substitution algorithms.
  	"""
  	def __init__(self, input = []):
  		"""
  		Algorithm Constructor.
  
  		Parameters
  		----------
  		input : list
  			A list containing the the input page swap. 
  		"""
  		if not input: #If the list is empty throw an exception.
  			raise ValueError("The list must not be empty") #throws the exception.
  		self.blocks = input[0] #Store the page frames size.
  		self.pages = input[1:] #Store the pages to swap.
  		self.missingPages = self.blocks #Count the lack of pages.
  
  	def removeChuncks(self, list, start, stop):
  		"""
  		Remove a piece of a list.
  
  		Parameters
  		----------
  		list : list
  			The list to delete the elements
  		start : int
  			start point.
  		stop : int
  			stop point.
  		"""
  		del list[start:stop] #Delete range
  
  	def preparePageFrame(self):
  		"""
  		Prepare the page frames.
  
  		Returns
  		-------
  		list
  			The list with initialized Page frames
  		"""
  		pageFrame = [None] * self.blocks #Create the page frame with elements passed by the user.
  		iterator = 0
  		for i in range(0, len(self.pages)):
  			if self.pages[i] not in pageFrame:
  				pageFrame[iterator] = self.pages[i]
  				iterator = iterator + 1
  				if iterator == self.blocks:
  					self.removeChuncks(self.pages, 0, i) #Remove part of the list that is on the page frame
  					break
  
  		return pageFrame #Return the list
  
subject: Fix logic error under preparePageFrames