Also note that constant won't let you declare constants like $1. These kinds of variables have special properties and declaring them constant would be a bad thing, if even possible.

And constants are not used like normal variables:

# You don't declare a constant like this:
use constant $FOO => 1;  # bad

# You do it this way
use constant FOO => 1;

# And use it like this:
print FOO;
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