Get the last key in the python dictionary

To get the last element from an arbitrary collection:

   & gt; & gt; & gt;  d = { 'a' :  1 ,  'b' :  & gt; & gt; & gt;   Import  collections  & gt; & gt; & gt;  [Last] = collections.deque (D, maxlen =  1 )   & gt; & gt; & gt;  Last  'b'      
 this o (n) in time, o (1) in memory the algorithm. For comparison:  list (d) [-1]  requires O (n) memory. 
  
 to Pytho 3.7, the keys in the dictionary are not ordered, so the concept of "last" "" ""  dict : 
  
   & gt; & gt;   from  collections  Import  orDereddict  & gt; & gt; & gt;  d = orDereddict (a =  1 , b =  2 ) # python 3.6 kwargs Order    & gt; & gt; & gt;  Last =  next  ( reversed  (d))   & gt; & gt; & gt;  Last  'b'      
 this is the optimal O (1) time and memory algorithm. Perhaps in the future this code will also work for the built -in DICT: