Outlined all of the tests I believe need to be created.
should add non-existing age to output_array
should add one if age exists in output_array
should only write to output if index has data associated to it
should write out in format 'integer,integer'
tests will now create a testfile and then delete it once done.
should create the front_half file
should create the back_half file
should split a file into two even parts
should reject invalid data
should accept valid data
should be able to combine data sets
Removed extra whitespace.