'Check to see if a particular key exists within the bucket.
Returns: An instance of a Key object or None
:type key_name: string
:param key_name: The name of the key to retrieve
:type version_id: string
:param version_id: Unused in this subclass.
:type stream_type: integer
:param stream_type: Type of the Key - Regular File or input/output Stream
:rtype: :class:`boto.file.key.Key`
:returns: A Key object from this bucket.'

def get_key(self, key_name, headers=None, version_id=None, key_type=Key.KEY_REGULAR_FILE):

    if (key_name == '-'):
        return Key(self.name, '-', key_type=Key.KEY_STREAM_READABLE)
    else:
        fp = open(key_name, 'rb')
        return Key(self.name, key_name, fp)
