This is pdfTeX, Version 3.141592653-2.6-1.40.22 (TeX Live 2021) (preloaded format=pdflatex 2021.8.24)  29 JAN 2022 14:56
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 file:line:error style messages enabled.
 %&-line parsing enabled.
**hal_prefs_lab.tex
(./hal_prefs_lab.tex
LaTeX2e <2020-10-01> patch level 4
L3 programming layer <2021-02-18>

./hal_prefs_lab.tex:3: LaTeX Error: \usepackage before \documentclass.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.3 \usepackage{
                beamerthemesplit}
? 
./hal_prefs_lab.tex:3: Emergency stop.
 ...                                              
                                                  
l.3 \usepackage{
                beamerthemesplit}
\usepackage may only appear in the document preamble, i.e.,
between \documentclass and \begin{document}.

 
Here is how much of TeX's memory you used:
 17 strings out of 478994
 549 string characters out of 5858184
 283044 words of memory out of 5000000
 17602 multiletter control sequences out of 15000+600000
 403430 words of font info for 27 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 13i,0n,15p,49b,14s stack positions out of 5000i,500n,10000p,200000b,80000s
./hal_prefs_lab.tex:3:  ==> Fatal error occurred, no output PDF file produced!