# go through a text file, looking for hidden Beatles lyrics
# and it will work with any bit of lyrics we ask it to search for

# example:  searchLyrics("TopSecretMilitaryInfo.txt","I am the Walrus")

class TheBeatDoesntGoOnException (Exception) :
    pass

# notice the lack of print(), I would never make a mistake and need to put
# in print() to debug it

def searchLyrics(src,lyric) :
    '''Given a file path and a string with some lyrics, go through the file looking for the emedded lyrics (in order), and return True or raise a TheSongDoesntGoOnException.'''
    s = open(src,"r")
    # split the words up, assuming that lyric has words separated by spaces
    words = lyric.split(" ")
    line = s.readline()
    # str.find() returns -1 when it doesn't find something, which is
    # "before" the first character in the string.  We use this as the
    # position of the last-found word
    lastFoundIndex = -1
    for word in words:
        while line.find(word) <= lastFoundIndex :
            # when the word is not found, we go to the next line,
            # resetting the location of the last find to the beginning of the line
            line = s.readline()
            lastFoundIndex = -1
            # if the line is empty, we got to the end of the file without
            # finding all the words, so we raise an exception
            if line == "" : raise TheBeatDoesntGoOnException
        # we only exit the while loop after finding a word, so we need to
        # reset the lastFoundIndex, and we DO NOT read another line,
        # first searching for the next word LATER in the current line
        lastFoundIndex = line.find(word)
    # if we get through all of the words, then we have found the lyrics!
    return True