code: func PutChar(x, y int, r rune) bool {
  	if InClipRect(x, y) {
  		term.SetCell(x, y, r, canvas.textColor, canvas.backColor)
  		return true
  	}
  
  	return false
  }
docs: // PutChar sets value for the Canvas cell: rune and its colors. Returns result of
  // operation: e.g, if the symbol position is outside Canvas the operation fails
  // and the function returns false