do BLOCK
            Not really a function. Returns the value of the last command in
            the sequence of commands indicated by BLOCK. When modified by
            the "while" or "until" loop modifier, executes the BLOCK once
            before testing the loop condition. (On other statements the loop
            modifiers test the conditional first.)

            "do BLOCK" does *not* count as a loop, so the loop control
            statements "next", "last", or "redo" cannot be used to leave or
            restart the block. See perlsyn for alternative strategies.

    do EXPR Uses the value of EXPR as a filename and executes the contents
            of the file as a Perl script.

                do 'stat.pl';

            is largely like

                eval `cat stat.pl`;

            except that it's more concise, runs no external processes, keeps
            track of the current filename for error messages, searches the
            @INC directories, and updates %INC if the file is found. See
            "@INC" in perlvar and "%INC" in perlvar for these variables. It
            also differs in that code evaluated with "do FILENAME" cannot
            see lexicals in the enclosing scope; "eval STRING" does. It's
            the same, however, in that it does reparse the file every time
            you call it, so you probably don't want to do this inside a
            loop.

            If "do" can read the file but cannot compile it, it returns
            "undef" and sets an error message in $@. If "do" cannot read the
            file, it returns undef and sets $! to the error. Always check $@
            first, as compilation could fail in a way that also sets $!. If
            the file is successfully compiled, "do" returns the value of the
            last expression evaluated.

            Inclusion of library modules is better done with the "use" and
            "require" operators, which also do automatic error checking and
            raise an exception if there's a problem.

            You might like to use "do" to read in a program configuration
            file. Manual error checking can be done this way:

                # read in config files: system first, then user
                for $file ("/share/prog/defaults.rc",
                           "$ENV{HOME}/.someprogrc")
                {
                    unless ($return = do $file) {
                        warn "couldn't parse $file: $@" if $@;
                        warn "couldn't do $file: $!"    unless defined $return;
                        warn "couldn't run $file"       unless $return;
                    }
                }