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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 build_sdist(sdist_directory, config_settings=None):
 """Builds an sdist, places it in sdist_directory"""

    poetry = Poetry.create(".")

    path = SdistBuilder(poetry, SystemEnv(Path(sys.prefix)), NullIO()).build(
        Path(sdist_directory)
    )

    return unicode(path.name)