Adding words to end/start of line Script

I need a script (preferably python in .py script format) to do the following. Text file 1 is a list of words e.g. word1 word2 word3 etc. Text file 2 is another list of words e.g. add1 add2 add3 The script should merge the 2 files by adding each word from file 2, to the start OR end of words in file 1. e.g. word1 add1 word1 add2 word1 add3 word2 add1 word2 add2 word2 add3 word3 add1 word3 add2 word3 add3 The script should be able to control whether the words from file 2 are added at the start or end of words in file 1. e.g. word1 add1 (end) VS. add1 word1 (start). That's it.