$time{2016}{November}{03}{sales} = 2500;

##</code><code>##

if(!defined $hash_ref->{$block}->{$libName}) {
   print "This is a test\n";
}

##</code><code>##

if(exists $hash_ref{$block} and !defined $hash_ref{$block}{$libName}) {
   print "This is a test\n";
}