Function interp_as_namespace 

fn interp_as_namespace(
    args: &[RValue],
    _named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Get a namespace environment by name (string → environment).

Delegates to the same logic as getNamespace(): checks loaded namespaces, attempts to load unloaded namespaces, and falls back to the base environment for built-in namespaces.

@param ns character scalar: namespace name @return environment @namespace base