aiosignal 1.4.0

Description

Signal is a list of registered asynchronous callbacks.

The signal's life-cycle has two stages: after creation its content could be
filled by using standard list operations: sig.append() etc.

After you call sig.freeze() the signal is frozen: adding, removing and dropping
callbacks is forbidden.

The only available operation is calling the previously registered callbacks by
using await sig.send(data).