def create_tokens(expression, /):
    """Convert a reverse polish expression in a list of tokens, using spaces
    to separate tokens.
    
    A token is converted to float if is a valid float, otherwise the token
    is pushed to the list.
    """

    tokens = []
    
    for part in expression.split(" "):
        try:
            tokens.append(float(part))
        except:
            tokens.append(part)
    
    return tokens