group 0 in the re module

[Yingjie Lan]

Hi, 

According to the doc, group(0) is the entire match.

>>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist") 
>>> m.group(0) # The entire match 'Isaac Newton' 

But if you do this:
>>> import re
>>> re.sub(r'(\d{3})(\d{3})', r'\0 to \1-\2', '757234')
'\x00 to 757-234'

where I expected
'757234 to 757-234'

Then I found that in python re '\0' is considered an octal number.
So, is there anyway to refer to the entire match by an escaped
notation?

Thanks,

Yingjie