Changed string concat to format(). Static method.

Author: Aralox

pythonforandroid/toolchain.py

@@ -576,10 +576,11 @@ def add_parser(subparsers, *args, **kwargs):
         # Each subparser corresponds to a method
         getattr(self, args.subparser_name.replace('-', '_'))(args)
 
-    def warn_on_carriage_return_args(self, args):
+    @staticmethod
+    def warn_on_carriage_return_args(args):
         for check_arg in args:
             if '\r' in check_arg:
-                warning("Argument '" + str(check_arg.replace('\r', '')) + "' contains a carriage return (\\r).")
+                warning("Argument '{}' contains a carriage return (\\r).".format(str(check_arg.replace('\r', ''))))
                 warning("Invoking this program via scripts which use CRLF instead of LF line endings will have undefined behaviour.")
 
     def warn_on_deprecated_args(self, args):