import re


class Phrase:
    """A class to represent phrases."""

    def __init__(self, content):
        self.content = content

    def ispalindrome(self):
        """Return True for a palindrome, False otherwise."""
        return self.processed_content() == reverse(self.processed_content())

    def processed_content(self):
        """Return content for palindrome testing."""
        return self.content.lower()

    def letters(self):
        """Return the letters in the content."""
        the_letters = []
        for character in self.content:
            if re.search(r"[a-zA-Z]", character):
                the_letters.append(character)
        return "".join(the_letters)

def reverse(string):
    """Reverse a string."""
    return "".join(reversed(string))