or download this
perl -d:DumpTrace=+Number::Format -MNumber::Format -E 'say Number::For
+mat::format_number(-0.00004, 5)'
>>> -e:1:[__top__]: say Number::Format::format_number(-0.00004, 5
+)
>>> Number/Format.pm:316:[_get_self]: unless (ref $_:(-4e-05,5)[0
+] && UNIVERSAL::isa($_:(-4e-05,5)[0], "Number::Format"))