before the loopthe accumulator variable message is initialized to be an empty stringthat is string that contains no characters (""each time through the loop number from the input is converted into an appropriate character and appended to the end of the message constructed so far the algorithm seems simple enoughbut even the first step presents us with problem how exactly do we get the sequence of numbers to decodewe don' even know how many numbers there will be to solve this problemwe are going to rely on some more string manipulation operations firstwe will read the entire sequence of numbers as single string using input then we will split the big string into sequence of smaller stringseach of which represents one of the numbers finallywe can iterate through the list of smaller stringsconvert each into numberand use that number to produce the corresponding unicode character here is the complete algorithmget the sequence of numbers as stringinstring split instring into sequence of smaller strings message "for each of the smaller stringschange the string of digits into the number it represents append the unicode character for that number to message print message this looks complicatedbut python provides some functions that do just what we need you may have noticed all along that 've been talking about string objects remember from last objects have both data and operations (they "know stuff,and "do stuff "by virtue of being objectsstrings have some built-in methods in addition to the generic sequence operations that we have used so for we'll use some of those abilities here to solve our decoder problem for our decoderwe will make use of the split method this method splits string into list of substrings by defaultit will split the string wherever space occurs here' an examplemystring "hellostring methods!mystring split(['hello,''string''methods!'naturallythe split operation is called using the usual dot notation for invoking one of an object' methods in the resultyou can see how split has turned the original string "hellostring methods!into list of three substringsstrings"hello,""string"and "methods!by the waysplit can be used to split string at places other than spaces by supplying the character to split on as parameter for exampleif we have string of numbers separated by commaswe could split on the commas " , , , split(","[' '' '' '' 'since our decoder program should accept the same format that was produced by the encoder programnamely sequence of numbers with spaces betweenthe default version of split works nicely