code: def cons(head_ele,l,**kwargs):
      '''
          from elist.elist import *
          ol=[1,2,3,4]
          id(ol)
          new = cons(5,ol)
          new
          id(new)
          ####
          ol=[1,2,3,4]
          id(ol)
          rslt = cons(5,ol,mode="original")
          rslt
          id(rslt)
      '''
      if('mode' in kwargs):
          mode = kwargs['mode']
      else:
          mode = "new"
      return(prepend(l,head_ele,mode=mode)f cons(head_ele,l,**kwargs):
      '''
          from elist.elist import *
          ol=[1,2,3,4]
          id(ol)
          new = cons(5,ol)
          new
          id(new)
          ####
          ol=[1,2,3,4]
          id(ol)
          rslt = cons(5,ol,mode="original")
          rslt
          id(rslt)
      '''
      if('mode' in kwargs):
          mode = kwargs['mode']
      else:
          mode = "new"
      return(prepend(l,head_ele,mode=mode))
docs: from elist.elist import *
          ol=[1,2,3,4]
          id(ol)
          new = cons(5,ol)
          new
          id(new)
          ####
          ol=[1,2,3,4]
          id(ol)
          rslt = cons(5,ol,mode="original")
          rslt
          id(rslt)