def _mergeparallel(inputfiles=None, outputfile=None):
    """ This merges Procar files seperated between k-point ranges.
    Happens with parallel Abinit runs. 
    """
    print('Merging parallel files...')
    filenames = sorted(inputfiles)
    with open(outputfile, 'w') as outfile:
        for fname in filenames:
            with open(fname) as infile:
                for line in infile:
                    outfile.write(line)
