code: def mimetype(self, value: str) -> None:
          
          if (
                  value.startswith('text/') or value == 'application/xml' or
                  (value.startswith('application/') and value.endswith('+xml'))
          ):
              mimetype = f"{value}; charset={self.charset}"
          else:
              mimetype = value
          self.headers['Content-Type'] = mimetype
docs: Set the mimetype to the value.