Working with CSV files

1: open CSV file, located on hard drive. this file has 4 to 5 different things in it's header 2: using a pre defined dictionary{key:value} look at a specific location in each row of the csv file (ie.. row[1] ) 3: if the str of data in that location matches one of the key's in the dictionary, I want to write a new_file which includes all of the original data in the row + I want to insert the matching key,value and place that in the rows data at position row[3] 4 if the str of data DOES not match any of the keys in the key_list than I want to write a different file to including all the original data (of the rows that do not have a match) I will supply a simple csv file with a short list of data so that you can work with it 5. So I want to open a csv file scan it and than create 2x new files, 1x file that matches the key_list, and 1x file that does not have any matches from the key_list 6. the header should of course be the first line in both new files