Implements `pipe-buffered`, a new primitive that allows accumulating
values from multiple input streams into internal series buffers before
executing a user-provided lambda. This is useful for implementing
lookback logic and ensuring that the lambda only executes when
sufficient data is available in all input streams.
The function takes a `lookback` integer, input streams, and a lambda.
The lambda receives `Series` objects for each input, allowing indexed
access to past values. The `pipe-buffered` function manages the
buffering and fill-gate logic.
Brummel
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