import re


def tokenize(text):
    """Parses a string into a list of semantic units (words)

    Args:
        text (str): The string that the function will tokenize.

    Returns:
        list: tokens parsed out by the mechanics of your choice
    """
    
    tokens = re.sub('[^a-zA-Z 0-9]', '', text)
    tokens = tokens.lower().split()
    
        
    return tokens