⊇ From r←x⊇y

If y is an array, x must be a either a simple array of integers or a array of nested simple arrays of integers; if x is simple, r is the major cells of y selected by the indices x (negative indices select from the end); if x is nested, r is an array with the same shape as x where each entry is the element indexed by the corresponding entry of x in y.

If y is a dictionary, each element of x is used as a key for ⌷ Index.