docs: def start(st_reg_number):
      """Checks the number valiaty for the São Paulo state"""
  
      divisor = 11
  
      verificador_one = int(st_reg_number[len(st_reg_number)-4])
      verificador_two = int(st_reg_number[len(st_reg_number)-1])
      weights_first = [1, 3, 4, 5, 6, 7, 8, 10]
      weights_secund = [3, 2, 10, 9, 8, 7, 6, 5, 4, 3, 2]
  
      if len(st_reg_number) > 13:
          return False
  
      if len(st_reg_number) < 12:
          return False
  
      if len(st_reg_number) == 12:
          sum_total = 0
          for i in range(len(st_reg_number)-4):
              sum_total = sum_total + int(st_reg_number[i]) * weights_first[i]
  
          rest_division = sum_total % divisor
          digit_first = rest_division
  
          if rest_division == 10:
              digit_first = 0
  
          num = 0
          mult = 10000000000
          for i in range(len(st_reg_number)-1):
              if i == 8:
                  num = num + digit_first * mult
              else:
                  num = num + int(st_reg_number[i]) * mult
              mult = mult/10
  
          if num < 10000000000:
              new_st = str('0') + str(num)
          else:
              new_st = str(num)
  
          sum_total = 0
          for i in range(len(new_st)):
              sum_total = sum_total + int(new_st[i]) * weights_secund[i]
  
          rest_division = sum_total % divisor
          digit_secund = rest_division
  
          if rest_division == 10:
              digit_secund = 0
  
          if digit_secund == verificador_two and digit_first == verificador_one:
              return True
          else:
              return False
  
      else:
          if st_reg_number[0] != "P":
              return False
  
          sum_total = 0
          for i in range(1, 9):
              sum_total = sum_total + int(st_reg_number[i]) * weights_first[i-1]
  
          digit = sum_total % divisor
  
          if digit == 10:
              digit = 0
  
          return digit == int(st_reg_number[len(st_reg_number)-4])