text: //@flow
  const x: {| [string]: number |} = {foo: 3}; // Ignores exact bars
  
  type Y = {| ...{[string]: number}, foo: number|};
  const y: Y = {foo: 3}; // No error
  
  type Z = $Exact<{[string]: number}>;
  const z: Z = {foo: 3}; // No error
  