my $var;
BEGIN {
   $var = ...;
}

##</code><code>##

my $var = "some value";
...
code that uses $var
...

##</code><code>##

my $var = "some value";
BEGIN {
   ...
   code that uses $var
   ...
}

##</code><code>##

my $var;
BEGIN {
   $var = "some value";
   ...
   code that uses $var
   ...
}

##</code><code>##

my $var; BEGIN { $var = "some value"; }

BEGIN {
   ...
   code that uses for $var
   ...
}