def _get_backend_instance(self, backend_cls):
<EOL>try:<EOL><INDENT>backend_instance = backend_cls(provider=self)<EOL><DEDENT>except Exception as err:<EOL><INDENT>raise QiskitError('<STR_LIT>' %<EOL>(backend_cls, err))<EOL><DEDENT>return backend_instance<EOL>
Return an instance of a backend from its class.

Args:
    backend_cls (class): Backend class.
Returns:
    BaseBackend: a backend instance.
Raises:
    QiskitError: if the backend could not be instantiated.