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

def _add_cli_param(params, key, value):
    '''
    Adds key and value as a command line parameter to params.
    '''
    if value is not None:
        params.append('--{0}={1}'.format(key, value))