# cirq.measurement_key¶

cirq.measurement_key(val: Any, default: Any = ([], ))[source]

Get the measurement key for the given value.

Parameters: val – The value which has the measurement key.. default – Determines the fallback behavior when val doesn’t have a measurement key. If default is not set, a TypeError is raised. If default is set to a value, that value is returned if the value does not have _measurement_key_. If val has a _measurement_key_ method and its result is not NotImplemented, that result is returned. Otherwise, if a default value was specified, the default value is returned. TypeError – val doesn’t have a _measurement_key_ method (or that method returned NotImplemented) and also no default value was specified.