title: Can't get these strings to add in Python
body: <p>I am trying to add these strings below, but I keep getting an error. I have tried a bunch of things and they work in other files with different settings, but I can't get it work here and I am not sure why. The issues is around the string "healthy_kibble". I want that to be the sum of "kibble" + 100. But everything I tried seems to give me different errors. Here are two examples</p>
  
  <pre><code>from sys import argv
  
  script, filename = argv
  
  def pickles_puppy(kibble, chicken):
      print(f"Pickles likes eating {kibble} pieces of kibble and {chicken} pieces of chicken")
  
  kibble = input("how many pieces of kibble does Pickles want?")
  chicken = input("and what about chicken?")
  infinity = 1000000
  
  pickles_puppy(kibble, chicken)
  
  f = open(filename, 'w')
  f.truncate()        
  
  healthy_kibble =  (kibble + 1 + 100)
  
  f.write(f'''Pickles is a little nugget \n
  if it was up to her shie would only eat {infinity} pieces of chicken \n
  But she has to be healthy \n
  So she also has to eat her {healthy_kibble} pieces of kibble''' )
  f.close()
  </code></pre>