<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def claim_keys(self, key_request, timeout=None):
 """Claims one-time keys for use in pre-key messages. Args: key_request (dict):
 The keys to be claimed. Format should be <user_id>: { <device_id>: <algorithm> }. timeout (int):
 Optional. The time (in milliseconds) to wait when downloading keys from remote servers. """

        content = {"one_time_keys": key_request}
        if timeout:
            content["timeout"] = timeout
        return self._send("POST", "/keys/claim", content=content)