code: def add_section(self, section):
          
          if section == self.default_section:
              raise ValueError('Invalid section name: %r' % section)
  
          if section in self._sections:
              raise DuplicateSectionError(section)
          self._sections[section] = self._dict()
          self._proxies[section] = SectionProxy(self, section)
docs: Create a new section in the configuration.
  
          Raise DuplicateSectionError if a section by the specified name
          already exists. Raise ValueError if name is DEFAULT.