module Stripe::APIOperations::Request::ClassMethods

def error_on_non_string_user_opts(opts)
OPTS_USER_SPECIFIED.each do |opt|
 unless opts.key?(opt)
= opts[opt]
 if val.nil?
 if val.is_a?(String)
e ArgumentError,
  "request option '#{opt}' should be a string value " \
    "(was a #{val.class})"