clear canves for testing errors or comparing two differnet stuff etc.

      <img src="http://www.htv.com.vn/CMSListPic/HTV-ThieuNhi/BeVuiHoc/2015/toc.jpg" class="hair_lion">
      <i class="http://www.htv.com.vn/CMSListPic/HTV-ThieuNhi/BeVuiHoc/2015/toc.jpg"></i>
      
      http://kids.nationalgeographic.com/explore/nature/10-cool-reasons-to-save-lions/
      http://www.htv.com.vn/CMSListPic/HTV-ThieuNhi/BeVuiHoc/2015/toc.jpg
      https://www.google.ca/search?q=why+should+we+save+the+lions&oq=why+should+save+the+lions&aqs=chrome.1.69i57j0l2.18101j0j7&sourceid=chrome&ie=UTF-8
      
      do the icon name= "icon_paw"