```ruby
module StartingBlocks
  class Runner

    def initialize options
      @contract = StartingBlocks::Contract.for options
    end

    def run_files files
      files = files.select { |x| @contract.extensions.include? x.split('/')[-1].split('.')[-1] }
      files = @contract.filter_these_files files 
      StartingBlocks.display "Files to run: #{files.inspect}"
      StartingBlocks::Publisher.publish_files_to_run files
      results = execute_these_files files
      StartingBlocks::Publisher.publish_results results
      puts results
      results
    end

    private

    def execute_these_files files
      @contract.execute_these_files files
    end

  end

end
```

Remove the period in the extension.
user
```ruby
module StartingBlocks
  class Runner

    def initialize options
      @contract = StartingBlocks::Contract.for options
    end

    def run_files files
      extensions = @contract.extensions.map { |x| x.gsub('.', '')
      files = files.select { |x| extensions.include? x.split('/')[-1].split('.')[-1] }
      files = @contract.filter_these_files files 
      StartingBlocks.display "Files to run: #{files.inspect}"
      StartingBlocks::Publisher.publish_files_to_run files
      results = execute_these_files files
      StartingBlocks::Publisher.publish_results results
      puts results
      results
    end

    private

    def execute_these_files files
      @contract.execute_these_files files
    end

  end

end
```
assistant