Fixed #28860 -- Removed unnecessary len() calls.

django/template/defaultfilters.py

@@ -568,7 +568,7 @@ def slice_filter(value, arg):
     try:
         bits = []
         for x in arg.split(':'):
-            if len(x) == 0:
+            if not x:
                 bits.append(None)
             else:
                 bits.append(int(x))

django/template/defaulttags.py

@@ -715,7 +715,7 @@ def firstof(parser, token):
     """
     bits = token.split_contents()[1:]
     asvar = None
-    if len(bits) < 1:
+    if not bits:
         raise TemplateSyntaxError("'firstof' statement requires at least one argument")
 
     if len(bits) >= 2 and bits[-2] == 'as':
@@ -1363,7 +1363,7 @@ def url(parser, token):
         asvar = bits[-1]
         bits = bits[:-2]
 
-    if len(bits):
+    if bits:
         for bit in bits:
             match = kwarg_re.match(bit)
             if not match: