title: Python doesnt add a string to a string and i dont get an error, even if i use it correctly
body: <p>So basically I am making an encrypter that uses the Vigenère square, but for some reason Python only stores the first letter of the message successfully and then while it does the commands and encrypts each character it doesn't add them in the message variable:</p>
  
  <pre><code>message=str()
  keyword="ΒΑΡΕΘΗΚΑ"
  string="ΑΝΚΑΤΑΦΕΡΕΣΝΑ"
  
  charNum=[913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923, 924, 925, 926, 927, 928, 929, 931, 932, 933, 934, 935, 936, 937]
  charTable={ "Α" : 0, "Β" : 1, "Γ" : 2, "Δ" : 3, "Ε" : 4, "Ζ" : 5, "Η" : 6, "Θ" : 7, "Ι" : 8, "Κ" : 9, "Λ" : 10, "Μ" : 11, "Ν" : 12, "Ξ" : 13, "Ο" : 14, "Π" : 15, "Ρ" : 16, "Σ" : 17, "Τ" : 18, "Υ" : 19, "Φ" : 20, "Χ" : 21, "Ψ" : 22, "Ω" : 23}
  
  
  i=0
  for char in string:
      character=charTable[char] + charTable[keyword[i]]
      if character &gt; 23:
          character -= 24
      message += chr(charNum[character])
      print(message)
  
      i+=1
      if i==len(keyword):
          i=0
  </code></pre>
  
  <p>Outputs:</p>
  
  <pre><code>Β
  Β
  Β
  Β
  Β
  Β
  Β
  Β
  Β
  Β
  Β
  Β
  Β
  </code></pre>
  
  <p>Which is supposed to show the message every time it adds a letter.</p>
  
  <p>If i change the </p>
  
  <pre><code>print(message)
  </code></pre>
  
  <p>to</p>
  
  <pre><code>print(chr(charNum[character]))
  </code></pre>
  
  <p>The output is this:</p>
  
  <pre><code>Β
  Ν
  Β
  Ε
  Β
  Η
  Ζ
  Ε
  Σ
  Ε
  Κ
  Ρ
  Θ
  </code></pre>
  
  <p>Which is each correctly encrypted letter.
  What is happening?</p>