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import { isFunction } from './is/function.ts';
type MessageFn = () => string;
/** * @name assert * @summary Checks for a valid test, if not Error is thrown. * @description * Checks that `test` is a truthy value. If value is falsy (`null`, `undefined`, `false`, ...), it throws an Error with the supplied `message`. When `test` passes, `true` is returned. * @example * <BR> * * ```javascript * const { assert } from '@polkadot/util'; * * assert(true, 'True should be true'); // passes * assert(false, 'False should not be true'); // Error thrown * assert(false, () => 'message'); // Error with 'message' * ``` */export function assert (condition: unknown, message: string | MessageFn): asserts condition {  if (!condition) {    throw new Error(      isFunction(message)        ? message()        : message    );  }}
/** * @name assertReturn * @description Returns when the value is not undefined/null, otherwise throws assertion error */export function assertReturn <T> (value: T | undefined | null, message: string | MessageFn): T {  assert(value !== undefined && value !== null, message);
  return value;}
/** * @name assertUnreachable * @description An assertion helper that ensures all codepaths are followed */export function assertUnreachable (x: never): never {  throw new Error(`This codepath should be unreachable. Unhandled input: ${x as unknown as string}`);}