parameters: (addr, ssl_version=PROTOCOL_TLS, ca_certs=None)
return_statement: return DER_cert_to_PEM_cert(dercert)
docstring: Retrieve the certificate from the server at the specified address,
      and return it as a PEM-encoded string.
      If 'ca_certs' is specified, validate the server cert against it.
      If 'ssl_version' is specified, use it in the connection attempt.
docstring_summary: Retrieve the certificate from the server at the specified address,
      and return it as a PEM-encoded string.
      If 'ca_certs' is specified, validate the server cert against it.
      If 'ssl_version' is specified, use it in the connection attempt.
docstring_tokens: Retrieve the certificate from the server at the specified address and return it as a PEM - encoded string . If ca_certs is specified validate the server cert against it . If ssl_version is specified use it in the connection attempt .
function: def get_server_certificate(addr, ssl_version=PROTOCOL_TLS, ca_certs=None):
      """Retrieve the certificate from the server at the specified address,
      and return it as a PEM-encoded string.
      If 'ca_certs' is specified, validate the server cert against it.
      If 'ssl_version' is specified, use it in the connection attempt."""
  
      host, port = addr
      if ca_certs is not None:
          cert_reqs = CERT_REQUIRED
      else:
          cert_reqs = CERT_NONE
      context = _create_stdlib_context(ssl_version,
                                       cert_reqs=cert_reqs,
                                       cafile=ca_certs)
      with  create_connection(addr) as sock:
          with context.wrap_socket(sock) as sslsock:
              dercert = sslsock.getpeercert(True)
      return DER_cert_to_PEM_cert(dercert)
function_tokens: def get_server_certificate ( addr , ssl_version = PROTOCOL_TLS , ca_certs = None ) : host , port = addr if ca_certs is not None : cert_reqs = CERT_REQUIRED else : cert_reqs = CERT_NONE context = _create_stdlib_context ( ssl_version , cert_reqs = cert_reqs , cafile = ca_certs ) with create_connection ( addr ) as sock : with context . wrap_socket ( sock ) as sslsock : dercert = sslsock . getpeercert ( True ) return DER_cert_to_PEM_cert ( dercert )