<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def unlock(path,
           zk_hosts=None,  # in case you need to unlock without having run lock (failed execution for example)
           identifier=None,
           max_concurrency=1,
           ephemeral_lease=False,
           scheme=None,
           profile=None,
           username=None,
           password=None,
           default_acl=None
           ):
    '''
    Remove lease from semaphore

    path
        The path in zookeeper where the lock is

    zk_hosts
        zookeeper connect string

    identifier
        Name to identify this minion, if unspecified defaults to hostname

    max_concurrency
        Maximum number of lock holders

    timeout
        timeout to wait for the lock. A None timeout will block forever

    ephemeral_lease
        Whether the locks in zookeper should be ephemeral

    Example:

    .. code-block: bash

        salt minion zk_concurrency.unlock /lock/path host1:1234,host2:1234
    '''
    # if someone passed in zk_hosts, and the path isn't in __context__['semaphore_map'], lets
    # see if we can find it
    zk = _get_zk_conn(profile=profile, hosts=zk_hosts, scheme=scheme,
                      username=username, password=password, default_acl=default_acl)
    if path not in __context__['semaphore_map']:
        __context__['semaphore_map'][path] = _Semaphore(zk, path, identifier,
                                                        max_leases=max_concurrency,
                                                        ephemeral_lease=ephemeral_lease)

    if path in __context__['semaphore_map']:
        __context__['semaphore_map'][path].release()
        del __context__['semaphore_map'][path]
        return True
    else:
        logging.error('Unable to find lease for path %s', path)
        return False