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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 get_files_in_dir(dir, *exts):
 """ Creates a list of files in a directory that have the provided extensions. :param dir: String path of directory containing files to be listed :param exts: Variable amount of string arguments specifying the extensions to be used. If none are provided, will default to finding every file in the directory :return: A list of string paths to each desired file in the directory. """

    file_paths = []
    if exts is None:
        exts = ['']
    for ext in exts:
        file_paths.extend(glob.glob(dir + '*' + ext))
    return file_paths