DB<1> $h1;

  DB<2> $h2 = {}

  DB<3> $h3 = {has => 'value'}

  DB<4> x $h1
0  undef
  DB<5> x $h2
0  HASH(0x8406f78)
     empty hash
  DB<6> x $h3
0  HASH(0x8406d08)
   'has' => 'value'