%Warning-MULTITOP: t/t_multitop_sig.v:14:8: Multiple top level modules
                                          : ... Suggest see manual; fix the duplicates, or use --top-module to select top.
                   ... Use "/* verilator lint_off MULTITOP */" and lint_on around source to disable this message.
                                          : ... Top module 'a'
module a(in, out);
       ^
                                          : ... Top module 'b'
module b(in, out);
       ^
                                          : ... Top module 'c'
module c(uniq_in, uniq_out);
       ^
%Error: Exiting due to