text: #!/usr/bin/env python3
  import json
  import sys
  
  if len(sys.argv) > 1:
      if sys.argv[1] == 'supports':
          # sys.argv[2] is the renderer name
          sys.exit(0)
  
  katex = '\n' + open('../.cargo/katex-header.html', 'r').read()
  context, book = json.load(sys.stdin)
  
  
  def fix(items):
      for section in items:
          if 'Chapter' in section:
              section['Chapter']['content'] += katex
              fix(section['Chapter']['sub_items'])
  
  
  fix(book['sections'])
  json.dump(book, sys.stdout)
  