Suppose you have a list of key/value pairs (i.e., a nested list where each element of the list is a (key value)pair. For example, the list might look like this: '((France Paris) (France Nice) (Spain Madrid) (Poland Krakow) (Poland Warsaw)) (Notice that the keys need not be unique for this problem.)Write a function named first-occurrence in Scheme that takes a key and a list then returns the value of the first item on the list with a matching key. Return '() if none of items on the list has a matching key.You must use either fold or reduce to do the vast majority of the work. You may use the built-in foldmethod by adding the line (require 'list-lib), or you can use your own implementation.The built-in fold function has parameters in this order: action partial-result lst.You may assume that the list contains an element with the key to be updated.For example,(first-occurrence 'Germany '((France Paris) (Germany Bonn) (Germany Berlin))) should return 'Bonn(first-occurrence 'Poland '((France Paris) (Germany Bonn) (Germany Berlin))) should return '()(first-occurrence 'Poland '()) should return '() Suppose you have a list of key/value pairs (i.e., a nested list where each element of the list is a (key value)pair. For example, the list might look like this: '((France Paris) (France Nice) (Spain Madrid) (PolandKrakow) (Poland Warsaw)) (Notice that the keys need not be unique for this problem.)Write a function named first-occurrence in Scheme that takes a key and a list then returns the value ofthe first item on the list with a matching key. Return '() if none of items on the list has a matching key.You must use either fold or reduce to do the vast majority of the work. You may use the built-in foldmethod by adding the line (require 'list-lib), or you can use your own implementation.The built-in fold function has parameters in this order: action partial-result lst.You may assume that the list contains an element with the key to be updated.For example,• (first-occurrence 'Germany '((France Paris) (Germany Bonn) (Germany Berlin))) shouldreturn 'Bonn• (first-occurrence 'Poland '((France Paris) (Germany Bonn) (Germany Berlin))) should return'()• (first-occurrence 'Poland '()) should return '()

Python which refers to the one it is a high-level, general-purpose programming language. Its design…

Answered: Suppose you have a list of key/value…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Suppose you have a list of key/value pairs (i.e., a nested list where each element of the list is a (key value)pair. For example, the list might look like this: '((France Paris) (France Nice) (Spain Madrid) (Poland Krakow) (Poland Warsaw)) (Notice that the keys need not be unique for this problem.)

Write a function named first-occurrence in Scheme that takes a key and a list then returns the value of the first item on the list with a matching key. Return '() if none of items on the list has a matching key.

You must use either fold or reduce to do the vast majority of the work. You may use the built-in foldmethod by adding the line (require 'list-lib), or you can use your own implementation.

The built-in fold function has parameters in this order: action partial-result lst.

You may assume that the list contains an element with the key to be updated.

For example,

(first-occurrence 'Germany '((France Paris) (Germany Bonn) (Germany Berlin))) should return 'Bonn
(first-occurrence 'Poland '((France Paris) (Germany Bonn) (Germany Berlin))) should return '()
(first-occurrence 'Poland '()) should return '()

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