def tribonacci_sequence.py

def tribonacci(signature, n):
    tribonacci_list = []
    if n == 0:
        return tribonacci_list
    
    if n == 1:
        tribonacci_list.append(signature[n-1])
        return tribonacci_list
    elif n == 2:
        for i in range(len(signature)-1):
            tribonacci_list.append(signature[i])
        return tribonacci_list
        
        for i in range(0,1):
            tribonacci_list.append(tribonacci_list[i] + tribonacci_list[i-1])
        return tribonacci_list
    else:
        for i in range(len(signature)):
            tribonacci_list.append(signature[i])

        for i in range(3,n):
            tribonacci_list.append(tribonacci_list[i-1] + tribonacci_list[i-2] + tribonacci_list[i-3])
        return tribonacci_list
 
def tribonacci(signature ,n):
    while len(signature) < n:
        signature.append(sum(signature[-3:]))
    
    return signature[:n]

def tribonacci(signature, n):
  res = signature[:n]
  for i in range(n - 3): res.append(sum(res[-3:]))
  return res

def tribonacci(signature,n):
    [signature.append(sum(signature[i-3:i])) for i in range(3,n)]
    return signature[0:n]