%Error: t/t_number_bad.v:8: Number is missing value digits: 32'd
   parameter integer FOO2 = 32'd-6;   
                            ^~~~
%Error: t/t_number_bad.v:9: Number is missing value digits: 32'd
   parameter integer FOO3 = 32'd;
                            ^~~~
%Error: t/t_number_bad.v:10: Number is missing value digits: 32'h
   parameter integer FOO4 = 32'h;
                            ^~~~
%Error: Exiting due to
