my ( $key,$value );

# or...

my ( %tips_by_name, %av_by_name, %max_by_name, %min_by_name );

##</code><code>##

my $key   = '';
my $value = '';
my %tips_by_name = '';
my %av_by_name = '';
my %max_by_name = '';
my %min_by_name = '';