title: How to update an image on a Canvas?
body: <p>This is the essence of the code I'm having trouble with: </p>
  
  <pre><code>camelot = Canvas(main, width = 400, height = 300)
  camelot.grid(row = 0, column = 0, rowspan = 11, columnspan = 3)
  MyImage = PhotoImage(file = "sample1.gif")
  camelot.create_image(0, 0, anchor = NW, image = MyImage)
  </code></pre>
  
  <p>This is run at the beginning. What I want to do on later in another function is replace <code>"sample1.gif"</code> by <code>"sample2.gif"</code>, and, possibly later on, replace that in turn by <code>"sample3.gif"</code>.  I'm stuck and nothing I've been trying has worked so far. </p>