class ActionController::Parameters

def deep_transform_keys(&block)

from the root hash and from all nested hashes and arrays. The values are unchanged.
results of running +block+ once for every key. This includes the keys
Returns a new +ActionController::Parameters+ instance with the
def deep_transform_keys(&block)
  new_instance_with_inherited_permitted_status(
    @parameters.deep_transform_keys(&block)
  )
end