class RuboCop::Cop::Rails::StrongParametersExpect

def require_key(require_method)
  if (first_argument = require_method.first_argument).respond_to?(:value)
    require_arg = first_argument.value
    separator = ': '
  else
    require_arg = first_argument.source
    separator = ' => '
  end
  "#{require_arg}#{separator}"
end