docs: function checkValueIsInObject(value, object, message) {
      checkNotEmpty(message, "No error message passed to checkValueIsInObject");
  
      var key = findValueInObject(value, object);
  
      if (typeof key === "undefined") {
          // Make sure the value's actually missing and it's not hidden behind undefined
          if (!(undefined in object && deepEquals(value, object[undefined]))) {
              throw new Error(message);
          }
      }
  }