Use GLib.List.deep_copy() to fix type-argument mismatch
lib/equation-parser.vala:79.9-79.43: error: Assignment: Cannot convert from `GLib.List<weak LexerToken>' to `GLib.List<LexerToken>'
this.token_list = token_list.copy();
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Compilation failed: 1 error(s), 0 warning(s)