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set method
Sets the header name to value.
Removes all existing values for the header named name and then adds value to it.
Implementation
void set(String name, Object value,
{@Since("2.8") bool preserveHeaderCase = false});
© 2012 the Dart project authors
Licensed under the BSD 3-Clause "New" or "Revised" License.
https://api.dart.dev/stable/2.18.5/dart-io/HttpHeaders/set.html