code: def faces(self, values):
          
          if values is None:
              values = []
          values = np.asanyarray(values, dtype=np.int64)
          # automatically triangulate quad faces
          if util.is_shape(values, (-1, 4)):
              log.info('triangulating quad faces')
              values = geometry.triangulate_quads(values)
          self._data['faces'] = values
docs: Set the vertex indexes that make up triangular faces.
  
          Parameters
          --------------
          values : (n, 3) int
            Indexes of self.vertices