Anagram Checker

In this lab, you'll implement a Python function named is_anagram. This function will determine whether two provided strings are anagrams of each other.

Function Requirements:

• Name: is_anagram
• Parameters: Two strings, str1 and str2.
• Output: The function should return a boolean value - True if str1 and str2 are anagrams, and False otherwise.
• Case Insensitivity: The function should treat uppercase and lowercase letters as the same.
• Non-Letter Characters: Non-letter characters (like spaces or punctuation) should not affect the outcome.

Examples:

1. is_anagram("Listen", "Silent") should return True.
2. is_anagram("Hello", "World") should return False.

Implement the is_anagram function considering these requirements. The lab challenges will test your function across different scenarios to ensure its correctness and efficiency.