old_contents: import re
  
  from regparser.layer.layer import Layer
  import settings
  
  
  class Meta(Layer):
      shorthand = 'meta'
  
      def __init__(self, tree, cfr_title, version, **context):
          super(Meta, self).__init__(tree, **context)
          self.cfr_title = cfr_title
          self.version = version
  
      def process(self, node):
          """If this is the root element, add some 'meta' information about
          this regulation, including its cfr title, effective date, and any
          configured info"""
          if len(node.label) != 1:
              return
  
          layer = {
              'cfr_title_number': self.cfr_title,
              'cfr_title_text': settings.CFR_TITLES[self.cfr_title]
          }
  
          if node.title:
              # up till the paren
              match = re.search('part \d+[^\w]*([^\(]*)', node.title, re.I)
              if match:
                  layer['statutory_name'] = match.group(1).strip()
              match = re.search('\(regulation (\w+)\)', node.title, re.I)
              if match:
                  layer['reg_letter'] = match.group(1)
  
          effective_date = self.effective_date()
          if effective_date:
              layer['effective_date'] = effective_date
  
          return [dict(layer.items() + settings.META.items())]
  
      def effective_date(self):
          if self.version and self.version.effective:
              return self.version.effective.isoformat()
  
new_contents: import re
  
  from regparser.layer.layer import Layer
  import settings
  
  
  class Meta(Layer):
      shorthand = 'meta'
  
      def __init__(self, tree, cfr_title, version, **context):
          super(Meta, self).__init__(tree, **context)
          self.cfr_title = cfr_title
          self.version = version
  
      def process(self, node):
          """If this is the root element, add some 'meta' information about
          this regulation, including its cfr title, effective date, and any
          configured info"""
          if len(node.label) != 1:
              return
  
          layer = {
              'cfr_title_number': self.cfr_title,
              'cfr_title_text': settings.CFR_TITLES[self.cfr_title]
          }
  
          if node.title:
              # up till the paren
              match = re.search('part \d+[^\w]*([^\(]*)', node.title, re.I)
              if match:
                  layer['statutory_name'] = match.group(1).strip()
              match = re.search('\(regulation (\w+)\)', node.title, re.I)
              if match:
                  layer['reg_letter'] = match.group(1)
  
          effective_date = self.effective_date()
          if effective_date:
              layer['effective_date'] = effective_date
  
          result = {}
          result.update(layer)
          result.update(settings.META)
          return [result]
  
      def effective_date(self):
          if self.version and self.version.effective:
              return self.version.effective.isoformat()
  
subject: Use dictionary update instead of addition