```{index} single: flowing; PDL::Core function ``` ```{index} single: PDL::Core::flowing; Perl function ``` # flowing `flowing($pdl)` — no-op stub, returns self. `flowing($pdl)` — enable forward-flow dataflow on this pdl. Sets `PDL_DATAFLOW_F` on the state flags. Upstream `Core.pm` semantics: trans created from this pdl retain their link so parent changes cascade to children. NOTE (Phase A status): we mark the flag and the slice/affine forward-flow path works (set → pdl_mark_children_dirty). Full trans-retention for non-affine transforms (e.g. `$a + $a`) is the remaining Phase A work — without it, `$pb = $pa + $pa; $pa ->set(...)` does not refresh $pb since the `+` trans was freed after its one-shot execution.