python string format suppress/silent keyerror/indexerror

Is there a way to use python string.format such that no exception is thrown when an index is missing, instead an empty string is inserted.

result = "i am an {error} example string {error2}".format(hello=2,error2="success")

here,result should be :

"i am an   example string success"

Right now, python throws a keyerror and stops formatting. Is it possible to change this behavior ?

Thanks

Edit:

There exists Template.safe_substitute (even that leaves the pattern intact instead of inserting an empty string) , but couldn't something similar for string.format

The desired behavior would be similar to string substitution in php.

class Formatter(string.Formatter):
  def get_value(self,key,args,kwargs):
    try:
        if hasattr(key,"__mod__"):
            return args[key]
        else:
            return kwargs[key]
    except:
        return ""

This seems to provide the desired behavior.