def clip_tweets(df, copy=True):
    """Clips the tweets in column 'tweet_text' by removing the url, route 
    indicator, and wsp boarding pass indicator.

    Args:
        df: Pandas dataframe with column 'tweet_text'
        copy: Bool - transform a copy of the dataframe

    Returns: a dataframe with column 'tweet_text' transformed
    """
    # copy the dataframe (or not)
    if copy == True:
        df = df.copy()
    
    # removing the url, 
    df['tweet_text'] = df['tweet_text'].str.replace('https:.*', '')

    # remove route indicator ('edm/king -'), extra whitespace
    df['tweet_text'] = df['tweet_text'].str.replace('edm/king -', '')
    df['tweet_text'] = df['tweet_text'].str.strip()

    # remove boarding pass indicator
    wsp_txt = ', no wsp boarding pass required|, wsp boarding pass required'
    df['tweet_text'] = df['tweet_text'].str.replace(wsp_txt, '')

    # return the dataframe
    return df