twsh

% Options for packages loaded elsewhere
\PassOptionsToPackage{unicode$for(hyperrefoptions)$,$hyperrefoptions$$endfor$}{hyperref}
\PassOptionsToPackage{hyphens}{url}
$if(colorlinks)$
\PassOptionsToPackage{dvipsnames,svgnames,x11names}{xcolor}
$endif$
$if(CJKmainfont)$
\PassOptionsToPackage{space}{xeCJK}
$endif$
%

twsh

import re
import sys

# open and read the first argument
with open(sys.argv[1], "r") as in_file:
    bibliography = in_file.read()

# Make sets of the citekeys found in the file, and of the entries
# The self_keys regex matches an upper or lower case cite, citep, citeyear, citeauthor,
# citeyearpar, and then anything between that and the first bracket