put

<< [a0 a1 ... ap] i any put >>
<< [a0 a1 ... ap] multi-index any put >>
<< s i any put >>
integer i; string s; array of integers multi-index;
The operator put <<any>> at the place i.
Example: /a [1 2 3] def  a 2 (Hi) put a :: --->[1 2 (Hi)]
Example: /a [[1 2] [3 4]] def  a [0 1] 10 put a :: --->
                                               [[1 10] [3 4]]