pipeline format

The pypyr pipeline format is simple, human-readable yaml.

title	description
pipeline structure	The format & structure of a pipeline.
comment	Annotations for pipeline authors.
decorators	Selectively run, skip, repeat, loop & handle errors on individual steps.
description	Descriptive text that prints to output when step runs.
foreach	Repeat step for each item in list.
in	Add arguments to context for the current step.
onError	Add custom error data on step error.
retry	Retry step until it succeeds.
run	Run this step only if condition True.
skip	Skip this step if condition True.
swallow	Swallow step error & continue with pipeline.
while	Repeat step until stop condition is `True` or up to the maximum iteration count.