def update(self, name: str, value=None, default=None, description: str=None):
if name in self._vars:<EOL><INDENT>description = description or self._vars[name].description<EOL>default = default or self._vars[name].default<EOL><DEDENT>elif name == '<STR_LIT:name>':<EOL><INDENT>raise ConfigError("<STR_LIT>")<EOL><DEDENT>v = _Var(name, description=description, default=default, defined=False)<EOL>v.value = value<EOL>self._vars[name] = v<EOL>
Like add, but can tolerate existing values; also updates the value.

Mostly used for setting fields from imported INI files and modified CLI flags.