input: Write a Python function that takes a string containing brackets as input. If each opening bracket has a matching closing bracket, return True. Otherwise, return False.
  assert validate_brackets("()")
  assert validate_brackets("(()())")
  assert validate_brackets("()()(()())()")
  assert validate_brackets("()()((()()())())(()()(()))")
  assert not validate_brackets("((()())))")
  assert not validate_brackets(")(()")
  assert not validate_brackets("(")
  assert not validate_brackets("((((")
  assert not validate_brackets(")")
  assert not validate_brackets("(()")
  assert not validate_brackets("()()(()())())(()")
  assert not validate_brackets("()()(()())()))()")
output: def validate_brackets(s):
      stack = []
      for char in s:
          if char == '(':
              stack.append('(')
          elif char == ')':
              if not stack:
                  return False
              stack.pop()
      return not stack