Function ncplane_perimeter_rounded 

pub fn ncplane_perimeter_rounded(
    plane: &mut NcPlane,
    stylemask: impl Into<NcStyle_u16>,
    channels: impl Into<NcChannels_u64>,
    boxmask: impl Into<NcBoxMask_u32>,
) -> NcResult_i32

Like ncplane_perimeter with the rounded box-drawing characters.

Method: NcPlane.perimeter_rounded().