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quiver/lib/core.dart

-// Copyright 2013 Google Inc. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-/**
- * Simple code with broad use cases.
- */
-library quiver.core;
-
-part 'src/core/hash.dart';
-part 'src/core/optional.dart';
-
-/**
- * Returns the first non-null argument. If all arguments are null, throws
- * an [ArgumentError].
- *
- * Note: if [o1] is an [Optional], this can be accomplished with `o1.or(o2)`.
- */
-firstNonNull(o1, o2, [o3, o4]) {
-  if (o1 != null) return o1;
-  if (o2 != null) return o2;
-  if (o3 != null) return o3;
-  if (o4 != null) return o4;
-  throw new ArgumentError('All arguments were null');
-}