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close method
Closes the sink.
The add method must not be called after this method.
Calling this method more than once is allowed, but does nothing.
Implementation
void close();
© 2012 the Dart project authors
Licensed under the BSD 3-Clause "New" or "Revised" License.
https://api.dart.dev/stable/2.18.5/dart-core/Sink/close.html