code: public function getDefinition()
      {
          return new FixerDefinition(
              'Whitespace around the keywords of a class, trait or interfaces definition should be one space.',
              [
                  new CodeSample(
                      '<?php
  
  class  Foo  extends  Bar  implements  Baz,  BarBaz
  {
  }
  
  final  class  Foo  extends  Bar  implements  Baz,  BarBaz
  {
  }
  
  trait  Foo
  {
  }
  '
                  ),
                  new VersionSpecificCodeSample(
                      '<?php
  
  $foo = new  class  extends  Bar  implements  Baz,  BarBaz {};
  ',
                      new VersionSpecification(70100)
                  ),
                  new CodeSample(
                      '<?php
  
  class Foo
  extends Bar
  implements Baz, BarBaz
  {}
  ',
                      ['single_line' => true]
                  ),
                  new CodeSample(
                      '<?php
  
  class Foo
  extends Bar
  implements Baz
  {}
  ',
                      ['single_item_single_line' => true]
                  ),
                  new CodeSample(
                      '<?php
  
  interface Bar extends
      Bar, BarBaz, FooBarBaz
  {}
  ',
                      ['multi_line_extends_each_single_line' => true]
                  ),
              ]
          );
      }
docs: {@inheritdoc}