class JMESPath::Nodes::SumFunction

def call(args)
  if args.count == 1 && args.first.respond_to?(:to_ary)
    args.first.to_ary.inject(0) do |sum, n|
      if Numeric === n
        sum + n
      else
        return maybe_raise Errors::InvalidTypeError, 'function sum() expects values to be numeric'
      end
    end
  else
    return maybe_raise Errors::InvalidArityError, 'function sum() expects one argument'
  end
end