We currently don't provide the API reference in this documentation anymore as it confused many people more than it helped them. The main reason for that is that the SDK is making heavy use of Stamps and there is just no proper way to document this in e.g. JSDoc right now.
However, there is a plan to get rid of Stamps and introduce TypeScript. Once the foundation is laid and it makes sense to publish the API reference this will be done. Until then you are better off taking a look into the sourcecode directly in case you face any uncertainties how to use functions!
If you want to help with the transition to TypeScript let us know! :-)