  class_sz is a versatile and robust code in C and Python that can compute
theoretical predictions for a wide range of observables relevant to
cross-survey science in the Stage IV era. The code is public at
https://github.com/CLASS-SZ/class_sz along with a series of tutorial notebooks
(https://github.com/CLASS-SZ/notebooks). It will be presented in full detail in
paper II. Here we give a brief overview of key features and usage.
