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

def start_volume(name, force=False):
    '''
    Start a gluster volume

    name
        Volume name

    force
        Force the volume start even if the volume is started
        .. versionadded:: 2015.8.4

    CLI Example:

    .. code-block:: bash

        salt '*' glusterfs.start mycluster
    '''
    cmd = 'volume start {0}'.format(name)
    if force:
        cmd = '{0} force'.format(cmd)

    volinfo = info(name)
    if name not in volinfo:
        log.error("Cannot start non-existing volume %s", name)
        return False

    if not force and volinfo[name]['status'] == '1':
        log.info("Volume %s already started", name)
        return True

    return _gluster(cmd)