Function warn_with_skip 

pub fn warn_with_skip(
    message: PyObjectRef,
    category: Option<PyTypeRef>,
    stack_level: isize,
    source: Option<PyObjectRef>,
    skip_file_prefixes: Option<PyTupleRef>,
    vm: &VirtualMachine,
) -> PyResult<()>

do_warn: resolve context via setup_context, then call warn_explicit.