/**
 * Check only for presence(not truthy) of a value.
 * Use in places where 0, false need to be considered valid.
 */
export declare function isPresent(value: any): boolean;
/**
 * checks if RTCPeerConnection constructor is available
 */
export declare const validateRTCPeerConnection: () => void;
/**
 * navigator.mediaDevices is undefined in insecure contexts served over HTTP protocol
 */
export declare const validateMediaDevicesExistence: () => void;