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{ # beginning of lexical scope

  my $foo;

} # end of lexical scope

{ # begin lexical scope

...

 $foo is: a string
$foo is: undefined

my $ref;
{ # begin lexical scope
...

$ref refers to: something in a lexical scope
$foo is: undefined

{
    my $foo = "a lexical variable";
...
 $bar is: a package variable
$foo is: undefined
$bar is: a package variable

use strict;
my $foo = "defined";
...

foo is undef during BEGIN phase
foo is defined at runtime

## lextut1.pl
my $foo = "in lextut1.pl's lexical file scope";

print "\$foo is: ", (defined $foo ? $foo : "undefined"), $/;

perl -e 'require "lextut1.pl"; \
         print "\$foo is: ", (defined $foo ? $foo : "undefined"), $/;'
$foo is: in lextut1.pl's lexical file scope
$foo is: undefined

sub foo
{ # begin lexical scope
...

$x in foo() is: a string
$x in bar() is: undefined

open(SRC, $0) or die("ack: $!");
my @lines = <SRC>;
...
bareword found: print
$w is: undefined
$line is: undefined

## otherwise $r would be auto-vifified as a package global
use strict;
...

Global symbol "$r" requires explicit package name at - line 1.
Execution of - aborted due to compilation errors.

my $foo = "file scope";
{
...
  $foo is: inner scope
 $foo is: outer scope
$foo is: file scope

my @list = qw(a list of words);
for my $w (@list) {
...
list: begins with a consonant
of: begins with a vowel
words: begins with a consonant

sub foo {
    print " \$x is: $x\n";
...

 $x is: altered state
$x is: original state

{ # begin lexical scope
  
...
 $x is: auto-vivified
$x is: undefined
$main::{x} is: *main::x

use IO::File;

...

print "\$foo is: ", (defined $foo ? $foo : "undefined"), $/;
a, comma, separated, list, of, words

{
  package foo;
...

 $x is: in foo
$foo::x is: in foo

## set stricture checking for the rest of the file scope
use strict;
...

    return $count;
}