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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_filename_extensions(url='https://www.webopedia.com/quick_ref/fileextensionsfull.asp'):
 """ Load a DataFrame of filename extensions from the indicated url ext description 0 .a UNIX static library file. 1 .asm Non-UNIX assembler source file. """

    df = get_longest_table(url)
    columns = list(df.columns)
    columns[0] = 'ext'
    columns[1] = 'description'
    if len(columns) > 2:
        columns[2] = 'details'
    df.columns = columns
    return df