Tries to decompose a parameterized 2q operation into √iSWAP's + parameterized 1q rotations.

Currently only supports decomposing the following gates: a) cirq.CZPowGate b) cirq.SwapPowGate c) cirq.ISwapPowGate d) cirq.FSimGate

op Parameterized two qubit operation to be decomposed into sqrt-iswaps.
use_sqrt_iswap_inv If True, cirq.SQRT_ISWAP_INV is used as the target 2q gate, instead of cirq.SQRT_ISWAP.

A parameterized cirq.OP_TREE implementing op using only cirq.SQRT_ISWAP (or cirq.SQRT_ISWAP_INV) and parameterized single qubit rotations OR None or NotImplemented if decomposition of op is not known.