Function interp_heap 

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

Create an empty max-heap (priority queue of numeric values).

Returns an integer ID with class “heap”. Use heap_push(), heap_pop(), etc. to manipulate it. The largest value is always at the top.

@return integer scalar with class “heap”