Are they balanced?

Problem

Code editors warn you when a line forgot to close a parenthesis. You are going to write that check.

Write a function that takes a text and returns true if every parenthesis, bracket and brace that opens has its own one closing it, in the right order.

The rules: "([{}])" is balanced and "([)]" is not, because the parenthesis closes before the bracket is done. Anything that is not one of those six characters does not count, so "(2 + 3)" is balanced. An empty text has nothing open, so with it you return true.

A hint: keep what you open in a list, and drop the last one every time something closes correctly.

Examples

• One pair

  "[]" → true

• Empty text

  "" → true

• Never closed

  "[[" → false

• Backwards

  "}{" → false

• Nested

  "{[]}" → true

• Closes the wrong one

  "{[])" → false

Besides these, the challenge has hidden tests that are revealed when you submit your solution.

You start with this

def is_balanced(text):
    pass

function isBalanced(text) {
}