Function interp_heap_pop 

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

Pop and return the maximum value from a max-heap.

Returns NULL if the heap is empty.

@param h integer scalar: heap ID @return numeric scalar (the max value), or NULL if empty