input: from typing import List
  
  def is_balance_negative(operations: List[int]) -> bool:
      """ Given an array of deposit and withdrawal transactions on a bank account that begins with
      a zero balance, determine if at any time the account balance goes into the negative. Return True
      if it does, otherwise return False.
      >>> is_balance_negative([1, 2, 3])
      False
      >>> is_balance_negative([1, 2, -4, 5])
      True
      """
output:     balance = 0
      for op in operations:
          balance += op
          if balance < 0:
              return True
      return False