Removes operations with tiny effects.

Used in the notebooks

Used in the tutorials

An operation op is considered to have a tiny effect if cirq.trace_distance_bound(op) <= atol.

circuit Input circuit to transform.
context cirq.TransformerContext storing common configurable options for transformers.
atol Absolute tolerance to determine if an operation op is negligible -- i.e. if cirq.trace_distance_bound(op) <= atol.

Copy of the transformed input circuit.