code: func (c *ColorM) Element(i, j int) float64 {
  	b, t := c.impl.UnsafeElements()
  	if j < ColorMDim-1 {
  		return float64(b[i+j*(ColorMDim-1)])
  	}
  	return float64(t[i])
  }
docs: // Element returns a value of a matrix at (i, j).