A palindrome is a word or phrase that reads the same forwards as it does backwards.
Write a python function to determine if a given string is a palindrome. Only consider letters (A-Z)
String to evaluate.
Boolean Value.
For e.g.
palindrome_checker('aIbohPhoBiA') True
and
palindrome_checker('hello_world') False
Test the palindrome_checker using the 50+ Palindrome Sentences found here at https://www.scarymommy.com/palindrome-sentences/ .