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const MOCK_SYMBOL = Symbol.for("@MOCK");
export type MockCall = {  args: any[];  returned?: any;  thrown?: any;  timestamp: number;  returns: boolean;  throws: boolean;};
export function fn(...stubs: Function[]) {  const calls: MockCall[] = [];
  const f = (...args: any[]) => {    const stub = stubs.length === 1      ? // keep reusing the first        stubs[0]      : // pick the exact mock for the current call        stubs[calls.length];
    try {      const returned = stub ? stub(...args) : undefined;      calls.push({        args,        returned,        timestamp: Date.now(),        returns: true,        throws: false,      });      return returned;    } catch (err) {      calls.push({        args,        timestamp: Date.now(),        returns: false,        thrown: err,        throws: true,      });      throw err;    }  };
  Object.defineProperty(f, MOCK_SYMBOL, {    value: { calls },    writable: false,  });
  return f;}
export function calls(f: Function): MockCall[] {  const mockInfo = (f as any)[MOCK_SYMBOL];  if (!mockInfo) throw new Error("callCount only available on mock functions");
  return [...mockInfo.calls];}