Change column names

import sys
import os

folder = sys.argv[1]
for path in os.listdir(folder):

    wiki_db = path.split('.')[0]
    full_path = os.path.join(folder, path)

    headers = None
    values = []

    with open(full_path, 'r') as input_file:
        for line in input_file:
            if headers is None:
                headers = line
            else:
                values.append(line)

    date_header, value_header = headers.strip().split('\t')
    headers = date_header + '\t' + wiki_db + '\n'

    with open(full_path, 'w') as output_file:
        output_file.write(headers)
        for line in values:
            output_file.write(line)