Macro offset 

macro_rules! offset {
    (delta=$delta:expr, chamfer=$chamfer:expr, $($child:expr);+;) => { ... };
    ($r:expr, $($child:expr);+;) => { ... };
}

Offsets a 2D shape.

#params

r: The radius of the offset.

delta: Used instead of r for sharp corners.

chamfer: Whether to extend a corner to a point (false) or chamfer it (true).

children: A list of Scad objects separated and ending with a semicolon.

expansion: A Scad struct literal.

#patterns

offset!(‘r: f64’, ‘children: Scad’;);

offset!(delta=‘delta: f64’, chamfer=‘chamfer: bool’, ‘children: Scad’;);