import re


def tokenize(library):
    """
    Function that takes a string of text a tokenizes it.
    The text is returned tokenized.
    """
    # Make sure all words are written with lower cases
    library = library.lower()
    # Remove non-alphabetic characters
    tokenizer = re.compile(r"\W+")
    # tokenize
    tokenized_library = tokenizer.split(library)

    return(tokenized_library)