text: """
  
  https://www.codewars.com/kata/556deca17c58da83c00002db
  
  Well met with Fibonacci bigger brother, AKA Tribonacci.
  
  As the name may already reveal, it works basically like a Fibonacci, but summing the last 3 (instead of 2) numbers of the sequence to generate the next. And, worse part of it, regrettably I won't get to hear non-native Italian speakers trying to pronounce it :(
  
  So, if we are to start our Tribonacci sequence with [1, 1, 1] as a starting input (AKA signature), we have this sequence:
  [1, 1 ,1, 3, 5, 9, 17, 31, ...]
  
  But what if we started with [0, 0, 1] as a signature? As starting with [0, 1] instead of [1, 1] basically shifts the common Fibonacci sequence by once place, you may be tempted to think that we would get the same sequence shifted by 2 places, but that is not the case and we would get:
  [0, 0, 1, 1, 2, 4, 7, 13, 24, ...]
  
  Well, you may have guessed it by now, but to be clear: you need to create a fibonacci function that given a signature array/list, returns the first n elements - signature included of the so seeded sequence.
  
  Signature will always contain 3 numbers; n will always be a non-negative number; if n == 0, then return an empty array (except in C return NULL) and be ready for anything else which is not clearly specified ;)
  
  If you enjoyed this kata more advanced and generalized version of it can be found in the Xbonacci kata
  
  *[Personal thanks to Professor Jim Fowler on Coursera for his awesome classes that I really recommend to any math enthusiast and for showing me this mathematical curiosity too with his usual contagious passion :)]*
  """
  
  
  def tribonacci(signature, n):
      trib = signature
      if n <= 0:
          return []
      elif n <= 2:
          return [signature[n]]
      else:
          for i in range(len(trib) - 1, n - 1):
              trib.append(trib[i] + trib[i - 1] + trib[i - 2])
      return trib
  