I assume this is to allow just one or the other (ClientMethods or Resources) to be defined, but if ClientMethods is not defined, `client_methods` will be nil, and the `.send(:include, client_methods)` will error, and then the `include resources` will not happen. 

Maybe instead,
```
if defined? module_name::ClientMethods
  Client.send(:include, module_name::ClientMethods)
end
# repeat for Resources
```