DeleteDuplicates¶

$ wo 'DeleteDuplicates[{a, b, a, c, b}]'
{a, b, c}

$ wo 'DeleteDuplicates[{1, 2, 1, 3, 2}]'
{1, 2, 3}

$ wo 'DeleteDuplicates[{1, 1, 1}]'
{1}

$ wo 'DeleteDuplicates[{a}]'
{a}

$ wo 'DeleteDuplicates[{}]'
{}