title: building a tower of * in python
body: <p>i'm working on this challenge, wherein based on a number given it will show the asterisk (*) increment per odd number. Basically the result should be if I run the function below and set the n_floor to 5 it should show the result below. My code somehow iterates per number of floor and increments the * per odd number but the result fails but this is because the spacing of the asterisk between those quotes are wrong. Any idea/tip how to fix this?</p>
  
  <p>a. Correct Result</p>
  
  <pre><code>['    *    ', '   ***   ', '  *****  ', ' ******* ', '*********']
  </code></pre>
  
  <p>b. REsult from my script below:</p>
  
  <pre><code>['*', '***', '*****', '*******', '*********']
  </code></pre>
  
  <pre><code>def tower_builder(n_floor):
      a = '*'
      b = 1
      c= 0
      result = []
      num=range(1, n_floor+1)
  
      # * to increment by odd number
      for x in num:
          c = a
          result.append(c)
          a += str('**')
      return result
  </code></pre>