code: def get(self, tags):
          
          # Try to find our name
          value = tags.get(self.name, '')
  
          for name in self.alternate_tags:
              # Iterate of alternates until a non-empty value is found
              value = value or tags.get(name, '')
  
          # If we still have nothing, return our default
          value = value or self.default
          return value
docs: Find an adequate value for this field from a dict of tags.