structured typesmutabilityand higher-order functions will print univs contains ['mit''caltech''rpi'which contains mit caltech rpi univs contains ['harvard''yale''brown'which contains harvard yale brown when we append one list to anothere techs append(ivys)the original structure is maintained the result is list that contains list suppose we do not want to maintain this structurebut want to add the elements of one list into another list we can do that by using list concatenation or the extend methode [ , , [ , , print ' =' extend( print ' =' append( print ' =' will print [ [ [ [ ]notice that the operator does not have side effect it creates new list and returns it in contrastextend and append each mutated figure contains short descriptions of some of the methods associated with lists note that all of these except count and index mutate the list append(eadds the object to the end of count(ereturns the number of times that occurs in insert(ieinserts the object into at index extend( adds the items in list to the end of remove(edeletes the first occurrence of from index(ereturns the index of the first occurrence of in it raises an exception (see if is not in pop(iremoves and returns the item at index in if is omittedit defaults to - to remove and return the last element of sort(sorts the elements of in ascending order reverse(reverses the order of the elements in figure methods associated with lists