Extending TypeScript Mapped Types to Support Multiple Contracts

type ParametersRefinements = {
  [K in ProductName as `is${K}`]: Refinement<Contract<any>, Contract<K>>
}

type ParametersRefinements = {
  [K in ProductName as `is${K}`]: Refinement<Contract<any>, Contract<K>>
}

type ParametersRefinements = {
  [K in ProductName as `is${K}`]: <C>(
    contract: C,
  ) => C extends Contract<any>
    ? contract is Contract<K>
    : contract is ReducedContract<K>
}

type ParametersRefinements = {
  [K in ProductName as `is${K}`]: <C>(
    contract: C,
  ) => C extends Contract<any>
    ? contract is Contract<K>
    : contract is ReducedContract<K>
}