def pangram_checker(text):
    # Part of Cosmos by OpenGenus Foundation
    # Arr is a list that contains a bool value
    # for each letter if it appeared in the sentence
    # If the entire list is true the string is a pangram.
    arr = [False] * 26;

    for c in text :
        if((c >= 'a' and c <= 'z') or (c >= 'A' and c <= 'Z')) :
            # The character is a letter.
            c = c.lower()
            c = ord(c) - ord('a')
            arr[c] = True

    # Checking if arr is all true value
    for index in arr :
        if not index :
            return False
    
    return True
