Devel::TraceFuncs provides utilities to trace the
       execution of a program.  It can print traces that look
       something like:

          +-> global: '0'
          |  +-> main::fo(4, 5) (in ./t.pm:32): 'now then'
          |  |  +-> main::fp(4, 5) (in ./t.pm:19)
          |  |  |  +-> main::fq() (in ./t.pm:13)
          |  |  |  |  que pee doll (in ./t.pm:8)
          |  |  |  +-< main::fq() (in ./t.pm:13)
          |  |  |  cee dee (in ./t.pm:14)
          |  |  +-< main::fp(4, 5) (in ./t.pm:19)
          |  |  ha
          |  |  hs (in ./t.pm:20)
          |  +-< main::fo(4, 5) (in ./t.pm:32): 'now then'
          |  done (in ./t.pm:34)
          +-< global: '0'