/**
 * Copy of `props` without the keys whose value is undefined, so spreading
 * the result cannot override downstream defaults with undefined (e.g.
 * `{ criterion: 'gini', ...treeProps }`). Needed because getParams() always
 * returns the full key set (with undefined for unset optional params) and
 * setParams()/clone() feed that back through the constructor.
 */
export declare function definedProps<T extends object>(props: T): T;