color(undef) semantics

• color(undef) propagates Noval (resets color), depth-first: outer always wins
• color("undef") (string) falls through to gray default
• color_module_definition default v is Noval (in scl.py)
• Detection: v is Noval or (isinstance(v, list) and v[0] == Noval)

Per-face color mapping for boolean operations

_map_face_colors() in scl_context.py maps source face colors through BRepAlgoAPI_Fuse/Cut/Common.

for list comprehensions and let expressions

• [ for (i = range) expr ] — list comprehension, parsed as expr_array_for
• let(a = val, b = val, ...) expr — local variable bindings, parsed as expr_let
• Both are expressions (not statements), usable inside [...] and anywhere an expression is expected
• for_loop (statement) uses expression for range (supports variables as range)
• let statement: let (a = val, b = val, ...) { block } — parsed as stat_let

rotate(a, v) — axis rotation

• rotate(a, [x,y,z]) — rotate by angle a around axis vector [x,y,z]
• Implemented manually in scl.py rotate handler: if 2+ positional args, extract a and v directly (bypassing parse_kwargs which only knows 1-param definition v=[x,y,z])
• scl_context.py rotate() accepts a=None, v=None kwargs; if a is not None, uses gp_Ax1 axis rotation instead of XYZ sequential
• Single arg rotate(s) treats scalar as rotation around Z axis