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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def install(runas=None):
    '''
    Install RVM system-wide

    runas
        The user under which to run the rvm installer script. If not specified,
        then it be run as the user under which Salt is running.

    CLI Example:

    .. code-block:: bash

        salt '*' rvm.install
    '''
    # RVM dependencies on Ubuntu 10.04:
    #   bash coreutils gzip bzip2 gawk sed curl git-core subversion
    installer = 'https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer'
    ret = __salt__['cmd.run_all'](
        # the RVM installer automatically does a multi-user install when it is
        # invoked with root privileges
        'curl -Ls {installer} | bash -s stable'.format(installer=installer),
        runas=runas,
        python_shell=True
    )
    if ret['retcode'] > 0:
        msg = 'Error encountered while downloading the RVM installer'
        if ret['stderr']:
            msg += '. stderr follows:\n\n' + ret['stderr']
        raise CommandExecutionError(msg)
    return True