How does opening files (open, three-arg open) interact with Unicode and encodings?

Opening files in Perl can interact with Unicode and encodings in specific ways, especially when using the three-argument form of the `open` function. The three-argument `open` allows you to specify the input and output layers, including encoding layers. This is crucial when working with Unicode data to ensure that characters are interpreted correctly.

# Example of opening a file with encoding in Perl
use strict;
use warnings;
use open ':std', ':utf8';  # Use UTF-8 encoding for input and output

my $filename = 'example.txt';

# Using three-argument open to specify encoding
open my $fh, '<:encoding(UTF-8)', $filename or die "Could not open '$filename': $!";
while (my $line = <$fh>) {
    print $line;  # Process the line
}
close $fh;