Inc. In processes user-entered labels that may contain spaces, punctuation, and mixed capitalization. Create a function that determines whether a string is a palindrome after normalization.
A normalized string keeps only alphanumeric characters and treats uppercase and lowercase letters as equal. Return True if the normalized string reads identically from left to right and right to left; otherwise, return False.
Implement is_palindrome(text), where text is a string. The function must return a boolean. An empty normalized string is considered a palindrome.
Use a two-pointer approach that compares characters from both ends while moving toward the center. Do not modify the input string in place.
def is_palindrome(text):