text: def beginning_zeros(string):
      '''
      You have a string that consist only of digits. You need to find how many zero digits ("0") are at the beginning of the given string.
  
  Input: A string, that consist of digits.
  
  Output: An Int.
  
  Precondition: 0-9
      '''
      count = 0
      lista = []
      lista2 = []
      lista.clear()
      lista =list(string)
      for c in lista:
          lista2.append(int(c))
      for c in lista2:
          if c==0:
              count=count+1
          if c!=0:
              break
      return count
  
  
  if __name__ == '__main__':
      print("Example:")
      print(beginning_zeros('100'))
      print(beginning_zeros('001'))
      print(beginning_zeros('100100'))
      print(beginning_zeros('001001'))
      
  