New post: Ruby Memoization

Here I would give some additional info, like:

> ### The boolean problem

> Since both nil and false are _falsy_ values when found in boolean expressions, you have to be carefull when memoizing boolens values.

```
f = false
=> false
f ||= true
=> true
```

> Or in a more real example:

```
  def has_credit?
    @has_credit ||= begin
      payload= BankApi.get_balance(self.user_bank_id)
      payload[:balance] > 0 # if this is false, the begin block will run again, and make uneeded calls for the bank api
    end
  end
```