Ben Weissman shows how to write extension methods in Biml:
An AstTableNode requires a schema to be valid, which is the only information that we can’t get from the AstFlatFileFormatNode so we’re defining a variable called UseSchema and pass it to our ToAstTableNode extension method.
But… how does that extension method work? MUCH easier than you might think.
Writing an extension method in C# isn’t tough either.