Why does FrozenDict.pop() return two values?

[andsteing]

What's the story behind this syntax?

_, init_params = init_variables.pop('params')

[andsteing]

Documentation on RTD: https://flax.readthedocs.io/en/latest/flax.core.frozen_dict.html

FrozenDict is our implementation of a Mapping that is immutable and suitable for use with parameters and other state variables. Additionally to function to convert between dict (and other Mapping) to FrozenDict via .freeze() and .unfreeze(), the FrozenDict class also implements a .pop() method that is similar to dict.pop() but with the difference that the updated FrozenDict is returned before the value that is popped (note that the default dict.pop() does this update in-place).