code: def writeFace(self, val, what='f'):
          
          # OBJ counts from 1
          val = [v + 1 for v in val]
          # Make string
          if self._hasValues and self._hasNormals:
              val = ' '.join(['%i/%i/%i' % (v, v, v) for v in val])
          elif self._hasNormals:
              val = ' '.join(['%i//%i' % (v, v) for v in val])
          elif self._hasValues:
              val = ' '.join(['%i/%i' % (v, v) for v in val])
          else:
              val = ' '.join(['%i' % v for v in val])
          # Write line
          self.writeLine('%s %s' % (what, val))
docs: Write the face info to the net line.