Quick demo of using the emit keyword to access a process output channel by name in a workflow
$ nextflow run main.nf
N E X T F L O W ~ version 23.04.2
Launching `main.nf` [nostalgic_volta] DSL2 - revision: 754b1f4043
executor > local (1)
[6a/ac0ee6] process > DO_FOO [100%] 1 of 1 ✔
[hello, /home/steve/.../foo.txt, goodbye]