Writes MetaPost code for the labels to
out_stream. It is called inPicture::output()(see Picture Reference; Outputting). Users should never need to call this function directly.When
Picture::output()is invoked, the MetaPost code forLabelsis written toout_streamafter the code for the drawing and filling commands. This prevents theLabelsfrom being covered up. However, they can still be covered by otherLabels, or byShapesorLabelsfrom subsequent invocations ofPicture::output()within the same figure (see I/O Functions, for descriptions ofbeginfig() and endfig()).