Python: Dictionary user$\_$ages contains four key$-$value pairs. Read a string from input, representing a key found in user$\_$ages. Then, assign the value associated with the key read with the current value minus $4.$

Ex: If the input is Abe, then the output is:

Original:

$\{\text{'}$Bob$\text{'}$: $14,$ 'Ben': $32,$ 'Abe': $42,$ 'Gus': $48\}$

Updated:

$\{\text{'}$Bob$\text{'}$: $14,$ 'Ben': $32,$ 'Abe': $38,$ 'Gus': $48\}$