objarray replace <obj> <index_start> <index_end> <obj_to_insert>
Replace the block from index_start to index_end by another objarray (that must be of the same type)
<obj> the objarray to be modified
<index_start> <index_end> integer indices of the block to be replaced
<obj_to_insert> objarray to be inserted
Warning: the values of <obj> itself are modified, without creating another copy of the object