[A,A,A, B,B, C,C]

i[]@array = {1,2,3,4,5};
int count;

for(int i=0; i<10; i++)
{
    count = i % len(i[]@array);
    insert(i[]@array,  count+=i , i[]@array[count]);
    
}
// return: [ 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0 ]

// need to expand the array size by a variable amount, so that its original elements are repeated evenly
// original array [A,B,C], expanded by 4 should return: [A,A,A,B,B,C,C]

i[]@array = {1,2,3,4,5};

int expand_count = chi("expand");
int input_len = len(i[]@array);
int output_len = input_len + expand_count;
// vex may well optimize this for us, but still a good habit to
// resize an array only once if we know the desired array size in advance
// rather than call append() or insert() inside a loop
resize(i[]@array, output_len);

for(int i=input_len; i>0; i--)
{
    // we want to write out the i-th input value to the highest 'unwritten'
    // output index until i doesn't fit in our unwritten range 
    int inner_loop = output_len/i;
    for(int j=0; j<inner_loop; j++)
    {
        // write the i-th input value to the end of the unwritten portion
        // of the output array
        i[]@array[output_len-1] = i[]@array[i-1];
        // reduce the size of the unwritten portion
        output_len--;
    }
}