How can i describe Custome Gate Sets in Cirq?

Question

i try to create a Custome GateSet with the CompilationTargetGateset class but it does not work.

cirq.convert_to_target_gateset(circuit, gateset=cirq.CompilationTargetGateset([cirq.rx,cirq.ry,cirq.ry,cirq.PhasedXZGate, cirq.CNOT]))

I tried to define a gate set with rotations in all directions, a phase gate and a CNOT. This should be a universal GateSet.

This is the error i get:

TypeError: Can't instantiate abstract class CompilationTargetGateset with abstract methods decompose_to_target_gateset, num_qubits

EDIT: Alright i found a code Example in the cirq repository here: https://github.com/quantumlib/Cirq/blob/v1.0.0/cirq-core/cirq/transformers/target_gatesets/compilation_target_gateset_test.py

Now my following question is how do i apply this to my problem. I don't know how to define a Gateset.