  # Optional packages which may be used with REST framework.
  psycopg2-binary>=2.8.2, <2.9
  markdown==2.6.11
  django-guardian==1.5.0
  django-filter>=2.1.0, <2.2
  coreapi==2.3.1
  coreschema==0.0.4
  pyyaml
 
</s> remove # Markdown is optional (version 2.6+ required)
 </s> add # Markdown is optional (version 3.0+ required) </s> remove         md.preprocessors.add('highlight', CodeBlockPreprocessor(), "_begin")
 </s> add         md.preprocessors.register(CodeBlockPreprocessor(), 'highlight', 40)
markdown==3.1.1
pygments==2.4.2
  # Optional packages which may be used with REST framework.
  psycopg2-binary>=2.8.2, <2.9
markdown==3.1.1
pygments==2.4.2
  django-guardian==1.5.0
  django-filter>=2.1.0, <2.2
  coreapi==2.3.1
  coreschema==0.0.4
  pyyaml
keep keep replace keep keep keep keep keep
 Update markdown preprocessor registration (#6722) 
requirements/requirements-optionals.txt