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

def unset(ctx, key):
    '''Removes the given key.'''
    file = ctx.obj['FILE']
    quote = ctx.obj['QUOTE']
    success, key = unset_key(file, key, quote)
    if success:
        click.echo("Successfully removed %s" % key)
    else:
        exit(1)