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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def all_files_exist(file_list):
 """Check if all files exist. :param file_list: the names of files to check. :type file_list: list :returns: ``True`` if all files exist, ``False`` otherwise. """

    all_exist = True
    for filename in file_list:
        all_exist = all_exist and os.path.isfile(filename)
    return all_exist