Scientific Computing with Python Projects - Arithmetic Formatter

Tell us what’s happening:
Hello, i’m starting with Python and I dont understand how to arrange my problem.

Your code so far

def split_list(x):
  l = []
  for i in x:
    z = i.split()
    for j in z:
      l.append(j)
  return(l)

def split_list_dig(x):
  L = []
  k = split_list(x)
  for i in k:
    if i == "+" or i == "-":
      continue
    else:
      L.append(i)
  return L

def arithmetic_arranger(x):
    #Debut condition de fonctionnement
    if len(x) > 5:
        return "Error: Too many problems"
    for i in range(len(x)):
      if x[i].find("+") > 0 or x[i].find("-") > 0:
        continue
      else:
        return "Error: Operator must be '+' or '-'"
    for i in split_list_dig(x):
        try:
          z = int(i)
        except:
          return "Error: Numbers must only contain digits"
        if len(i) <= 4:
            continue
        else:
            return "Error: Numbers cannot be more than four digits"
    digits = []
    try:
        for i in split_list_dig(x):
            z = int(i)
            digits.append(z)
    except:
            return "Error: Numbers must only contain digits"
    #Fin condition de fonctionnement
    #Debut calcul
    Y = "-"
    for i,j in zip(range(0,len(digits), 2), range(len(x))):
        if x[j].find("+") > 0:
          r1 = digits[i]
          r2 = digits[i+1]
          K1 = len(str(r1))
          K2 = len(str(r2))
          if K1 <= K2:
            print(str(r1).rjust(2*K2," "))
            print("+", str(r2).rjust(K2," ")) ; print(Y.rjust(K2+2,"-")) ; print("\n")
          elif K1 > K2:
            print(str(r1).rjust(2*K2," "))
            print("+", str(r2).rjust(K2," ")) ; print(Y.rjust(K1+3,"-")) ; print("\n")
        elif x[j].find("-")> 0 :
          r1 = digits[i]
          r2 = digits[i+1]
          K1 = len(str(r1))
          K2 = len(str(r2))
          if K1 <= K2:
            print(str(r1).rjust(6," "))
            print("+", str(r2).rjust(K2," ")) ; print(Y.rjust(K2 + 2,"-")) ; print("\n")
          elif K1 > K2:
            print(str(r1).rjust(6," "))
            print("+", str(r2).rjust(K2," ")) ; print(Y.rjust(K1,"-")) ; print("\n")
            
    #Fin calcul

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Challenge: Scientific Computing with Python Projects - Arithmetic Formatter

Link to the challenge:

An important thing to keep in mind is that you need to return the final result, not print it

thanks, I will do that.