for (int i = 0; i <= system_range.length (); i++)
{
item_indices.push_back (Slice (len, 0));
spanner_indices.push_back (Slice (len, 0));
}
for (int i = 0; i <= system_range.length (); i++)
{
item_indices.push_back (Slice (len, 0));
spanner_indices.push_back (Slice (len, 0));
}