def xblock_primary_child_category(xblock):
 category = xblock.category
 if (category == 'course'):
  return 'chapter'
 elif (category == 'chapter'):
  return 'sequential'
 elif (category == 'sequential'):
  return 'vertical'
 return None

def xblock_primary_child_category ( xblock ) : category = xblock . category if ( category == 'course' ) : return 'chapter' elif ( category == 'chapter' ) : return 'sequential' elif ( category == 'sequential' ) : return 'vertical' return None
returns the primary child category for the specified xblock .