title: Challenge task to use function find() and set()
body: <p>Use function find() and set()<br>
  takes an input string and Character to returns the Index of everytime that Character Appears</p>
  
  <p>example :</p>
  
  <pre><code>String :  'abcabcabc' 
  Character : 'c'
  Character Appears Index :[2,5,8]
  </code></pre>
  
  <p>i need to accomplish this task without using any library</p>
  
  <p>what i'm done </p>
  
  <pre><code>x = 'abcabcabc'
  y='c'
  z=[]
  
  if y in x:
      z.append(x.find(y))
  
  print(z)
  </code></pre>
  
  <p>but it's only print the first c index i need to code continue till the end of the string</p>