```ruby
require 'vcr'

VCR.configure do |c|
  c.cassette_library_dir = 'spec/fixtures/vcr'
  c.hook_into :webmock
  c.default_cassette_options = { serialize_with: :json, record: :once }
  c.debug_logger = File.open(Rails.root.join('log', 'vcr.log'), 'a')
  c.filter_sensitive_data('{WUNDERGROUND_KEY}') { ENV['WUNDERGROUND_KEY'] }
end
```

Switch to --- for placeholder because curlies do not parse
user
```ruby
require 'vcr'

VCR.configure do |c|
  c.cassette_library_dir = 'spec/fixtures/vcr'
  c.hook_into :webmock
  c.default_cassette_options = { serialize_with: :json, record: :once }
  c.debug_logger = File.open(Rails.root.join('log', 'vcr.log'), 'a')
  c.filter_sensitive_data('---WUNDERGROUND_KEY---') { ENV['WUNDERGROUND_KEY'] }
end
```
assistant