Run one validator from another

I am trying to build a validator for array e. g.

# complex validator, which will fail if array contains a string longer that allowed
class MyArrayValidator < Grape::Validations::Base
  def validate_param!(attr_name, params)
    if params[attr_name].any? { |element| element.size > @option }
      fail Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: "array should not contain strings longer than #{@option}"
    end
  end
end

But there is a length validator (described in docs), so it's definitely a good idea to reuse it like that:

class MyArrayValidator < Grape::Validations::Base
  def validate_param!(attr_name, params)
    params[attr_name].each do |element|
      run_validator!(element, length: @option)
    end
  end
end

Start with Grape::Validations::Base and the existing length validator described in the documentation. Determine how one validator can invoke another for each array element, then verify that the custom array validator reports the expected validation failure for an overlong string.