I want to create a regular expression for the dollar currency.
This examples should be find by regex:

```
$ 10 
10$
10 $
1000005 dollars

```

And this shouldn't be match:

```
dollars 33

```

I have already use this expressions:

```
r_dollar = r'(\$|\$usd|usd|dollar(s)?|bucks)'
number = '([1-9]([0-9])+)'
valuta_with_num = u'(({0})\s?{1})|({1}\s?({0}))'.format(number, r_dolar)
currency_tags = re.compile(u'({0})'.format(valuta_with_num))

```

How can I do this?