code: def get_ssl_certificate(
          self, binary_form: bool = False
      ) -> Union[None, Dict, bytes]:
          
          try:
              if self.connection is None:
                  return None
              # TODO: add a method to HTTPConnection for this so it can work with HTTP/2
              return self.connection.stream.socket.getpeercert(  # type: ignore
                  binary_form=binary_form
              )
          except SSLError:
              return None
docs: Returns the client's SSL certificate, if any.
  
          To use client certificates, the HTTPServer's
          `ssl.SSLContext.verify_mode` field must be set, e.g.::
  
              ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
              ssl_ctx.load_cert_chain("foo.crt", "foo.key")
              ssl_ctx.load_verify_locations("cacerts.pem")
              ssl_ctx.verify_mode = ssl.CERT_REQUIRED
              server = HTTPServer(app, ssl_options=ssl_ctx)
  
          By default, the return value is a dictionary (or None, if no
          client certificate is present).  If ``binary_form`` is true, a
          DER-encoded form of the certificate is returned instead.  See
          SSLSocket.getpeercert() in the standard library for more
          details.
          http://docs.python.org/library/ssl.html#sslsocket-objects