The program of Exercise P$8\mathrm{.}17$ is not very user$-$friendly because it requires the user to know the exact spelling of the country name. As an enhancement, whenever a user enters a single letter, print all countries that start with that letter. Use a dictionary whose keys are letters and whose values are sets of country names.

Use python, Keep the original program $($solution to Exercise P$8\mathrm{.}17)$ up to the creation of the incomes dictionary with the key $($country name$)$ and values $($per capita income$).$ Create a new dictionary $($letters$)$ with the key $($alphabet letter$)$ and values $($a set of the country names that start with the letter in the key$).$ Follow the steps below to create this dictionary:

$-$ iterate over the keys $($country names$)$ in the first dictionary $($incomes$)$ and if the first letter of the key $($country name$)$ is not a key in the new dictionary $($letters$)$

$-$ add a new entry to the dictionary: key: first letter of the country name,

value: an empty set and add the country name to the set, indexed by the first letter of the country name as the key

$-$ Modify the part for reading queries from the user and responding in the original program.

Follow the steps below for the user input and the program response:

$-$ Prompt the user for input

if the text entered by the user is of length $==1$:

$$ use the new dictionary $($letters$)$ to list the countries starting with that letter

$-$ else use the text entered by the user to look for the country name in the first

dictionary $($incomes$)$ and

$-$ if found print the per capita income

$-$ else print the text entered is not a recognized country

Here's what i have so far in python:

incomes $=\{\}$

inf $=$ open$("$rawdata$\_2004-1.$txt$","$r$")$

for line in inf:

parts $=$ line.split$("\backslash$t$")$

# Remove the dollar sign and comma.

parts$[2]=$ parts$[2].$replace$("$$$","")$

parts$[2]=$ parts$[2].$replace$(",","")$

# Add the country to the dictionary.

incomes$[$parts$[1].$upper$()]=$ float$($parts$[2])$

# Read queries from the user and respond to them.

country $=$ input$("$Enter a country name $($or type quit to quit$)$: $").$upper$()$

while country $!=$ "QUIT" :

if country in incomes :

print$("$The per capita income is$",$ incomes$[$country$])$

else :

print$("$That wasn't a recognized country."$)$

print$()$

# Read the next country from the user.

country $=$ input$("$Enter a country name $($or type quit to quit$)$: $").$upper$()$

letters $=\{\}$

for country in incomes.keys$()$:

first$\_$letter $=$ country$[0]$

if first$\_$letter not in letters:

letters$[$first$\_$letter$]=$ set$()$

letters$[$first$\_$letter$].$add$($country$)$

# Modified part for reading queries from the user and responding

while True:

user$\_$input $=$ input$("$Enter a country name or the first letter of a country: $")$

if len$($user$\_$input$)==1$: # If the user enters a single letter

letter $=$ user$\_$input.upper$()$

if letter in letters:

countries$\_$with$\_$letter $=\text{'},\text{'}.$join$($sorted$($letters$[$letter$]))$

print$($f$"$Countries starting with $\text{'}\{$letter$\}\text{'}$: $\{$countries$\_$with$\_$letter$\}")$

else:

print$($f$"$No countries found starting with $\text{'}\{$letter$\}\text{'}")$

else: # If the user enters a full country name

country$\_$name $=$ user$\_$input.capitalize$()$

if country$\_$name in incomes:

print$($f$"$The per capita income of $\{$country$\_$name$\}$ is $\{$incomes$[$country$\_$name$]\}")$

else:

print$($f$"$The entered text $\text{'}\{$user$\_$input$\}\text{'}$ is not a recognized country."$)$