text: class Book:
      
      def __init__(self, bTitle, bAuthor, bPages, bISBN, bCost, bSelling):
          self.title = bTitle
          self.author = bAuthor
          self.numPages = bPages
          self.isbn = bISBN
          self.costPrice = bCost
          self.numCopies = 0
          self.sellingPrice = bSelling
          
      def changePrice(self, newPrice):
          self.sellingPrice = newPrice
      
      def sellCopy(self):
          if self.numCopies == 0:
              print("There are no copies to sell")
          else:
              self.numCopies -= 1
          return self.sellingPrice
      
      def restockBook(self, numNewCopies):
          self.numCopies += numNewCopies
          return numNewCopies * self.costPrice
      
      def retrieveInformation(self):
          infoString = "Title: " + self.title
          infoString += "\nAuthor: " + self.author
          infoString += "\nNumber of Pages: " + str(self.numPages)
          infoString += "\nISBN: " + str(self.isbn)
          infoString += "\nCost Price: £" + str(self.costPrice)
          infoString += "\nSelling Price: £" + str(self.sellingPrice)
          infoString += "\nNumber of Copies: " + str(self.numCopies)
          
          return infoString
      