code: function isActive(
      location, indexOnlyOrDeprecatedQuery=false, deprecatedIndexOnly=null
    ) {
      let indexOnly
      if (
        (indexOnlyOrDeprecatedQuery && indexOnlyOrDeprecatedQuery !== true) ||
        deprecatedIndexOnly !== null
      ) {
        warning(
          false,
          '`isActive(pathname, query, indexOnly) is deprecated; use `isActive(location, indexOnly)` with a location descriptor instead. http://tiny.cc/router-isActivedeprecated'
        )
        location = { pathname: location, query: indexOnlyOrDeprecatedQuery }
        indexOnly = deprecatedIndexOnly || false
      } else {
        location = history.createLocation(location)
        indexOnly = indexOnlyOrDeprecatedQuery
      }
  
      return _isActive(
        location, indexOnly, state.location, state.routes, state.params
      )
    }
docs: Signature should be (location, indexOnly), but needs to support (path, query, indexOnly)