cirq.phase_by

Returns a phased version of the effect.

cirq.phase_by(
    val: Any,
    phase_turns: float,
    qubit_index: int,
    default: TDefault = RaiseTypeErrorIfNotProvided
)

For example, an X gate phased by 90 degrees would be a Y gate. This works by calling val's _phaseby method and returning the result.

Args
`val`	The value to describe with a unitary matrix.
`phase_turns`	The amount to phase the gate, in fractions of a whole turn. Multiply by 2π to get radians.
`qubit_index`	The index of the target qubit the phasing applies to. For operations this is the index of the qubit within the operation's qubit list. For gates it's the index of the qubit within the tuple of qubits taken by the gate's `on` method.
`default`	The default value to return if `val` can't be phased. If not specified, an error is raised when `val` can't be phased.

Returns
If `val` has a _phaseby method and its result is not NotImplemented, that result is returned. Otherwise, the function will return the default value provided or raise a TypeError if none was provided.

Raises
`TypeError`	`val` doesn't have a _phaseby method (or that method returned NotImplemented) and no `default` was specified.

Args