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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 infer_delimiter(filepath):
 """ From extension infer delimiter used in a separated values file. :param str filepath: path to file about which to make inference :return str | NoneType: extension if inference succeeded; else null """

    ext = os.path.splitext(filepath)[1][1:].lower()
    return {"txt": "\t", "tsv": "\t", "csv": ","}.get(ext)