Function transfers 

pub fn transfers(
    stages: &[RecognizedStage],
    m: &TpManifest,
) -> Vec<ChipTransfer>

The tensors that cross between m’s chips when each statement runs on TpManifest::chip_running its binder: for each statement, every operand the latest earlier statement to write it wrote on another chip, in program order, each (tensor, reader's chip) once. An operand no statement writes — a table, a host-written input — crosses nothing: each chip that reads it holds its own.