list L1, L2;

# Lists are heterogeneous:
l_append(L1, 3);
l_append(L1, "deep");

# and may contain self references.
# A self references in the last position:
l_link(L1, -1, L1);

# List may also contain mutual references.
# Create a new list in the last position:
l_n_list(L1, -1);
# Add a reference to the top level list to the nested list:
l_link(l_q_list(L1, -1), -1, L1);

# There are no limitations to the deep copy method:
l_copy(L2, L1);

# Modify the string in the original list,
# via the self reference in the 3rd position
l_r_text(l_q_list(L1, 2), 1, "copy");

# Show the string in the two lists:
o_text(l_query(L2, 1));
o_text(l_query(L1, 1));
o_byte('\n');

# And again, via the included self references:
o_text(l_query(l_query(L2, 2), 1));
o_text(l_query(l_query(L1, 2), 1));
o_byte('\n');