ArrayPad
ArrayPad[array,m] gives an array with m zeros of padding on every side.
ArrayPad[array,m,padding] uses the specified padding.
ArrayPad[array,{m,n},…] pads with m elements at the beginning and n elements at the end.
ArrayPad[array,{{m1,n1},{m2,n2},…},…] pads with mi, ni elements at level i in array.
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