re-pcre: Support .group() method without args.

Defaults to 0.

re-pcre/re.py

@@ -41,6 +41,8 @@ class PCREMatch:
         self.offsets = offsets
 
     def group(self, *n):
+        if not n:
+            return self.s[self.offsets[0]:self.offsets[1]]
         if len(n) == 1:
             return self.s[self.offsets[n[0]*2]:self.offsets[n[0]*2+1]]
         return tuple(self.s[self.offsets[i*2]:self.offsets[i*2+1]] for i in n)

re-pcre/test_re.py

@@ -2,6 +2,7 @@ import re
 
 m = re.search(r"a+", "caaab")
 assert m.group(0) == "aaa"
+assert m.group() == "aaa"
 
 m = re.match(r"(?ms)foo.*\Z", "foo\nbar")
 assert m.group(0) == "foo\nbar"