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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 step_an_empty_file_named_filename(context, filename):
 """ Creates an empty file. """

    assert not os.path.isabs(filename)
    command_util.ensure_workdir_exists(context)
    filename2 = os.path.join(context.workdir, filename)
    pathutil.create_textfile_with_contents(filename2, "")