Set routines

Hint

Making proper sets

`unique`	Find the unique elements of an array.
`unique_all`	Find the unique elements of an array, and counts, inverse, and indices.
`unique_counts`	Find the unique elements and counts of an input array x.
`unique_inverse`	Find the unique elements of x and indices to reconstruct x.
`unique_values`	Returns the unique elements of an input array x.