rfind implementation using find
<p>I am new to python and I am trying to implement rfind function using find.</p>

<pre><code>def rfind_imp(s,t):
    ss = s
    fpos = 0
    while(True):             
         fpos = s.find(t,fpos)
         ss=ss[fpos:]

         if(ss):    
           fpos = fpos +1    
         else:
           return fpos

print rfind_imp("I saw a donkey,I saw a saw "," ")
print "I saw a donkey,I saw a saw ".rfind(" ")
</code></pre>

<p>But the issue I am facing is I am getting 16th charcter as rfind value. Can some one help me find where I am doing a mistake. Also any suggestions for better implementation of rfind using find should be helpful.</p>
