[Fixed]-Saving Base64 String as .PNG not working

When you added the = to the string the returned string from .decode("base64") was the same as the input string minus the appended =.

To write the .png to a file you need to do the following:

head, data = chartStr.split(",", 1)
with open('foo.png',"wb") as f:
     f.write(data.decode('base64'))

This removes the data:image/png;base64, stuff and leaves you with some base64 encoded data.