def add_state_names(my_df):
    """
    Adds a column of state 
    names to accompany a corresponding column of state abbreviation 

    Params:
    my_df (pandas.DataFrame) has a column called "abbrev" with state abbreviation
    
    returns: 
    copy of the original dataframe, with another column
    """

    # Plan: 
    # add a column of corresponding state names
    # dict with abbreviation/name mapping 
    # create a new column that is a copy of the first, but mapped with names 
    # concat with axis=1 
    new_df = my_df.copy()

    names_map = {"CA": "California", "CT":"Connecticut", "CO": "Colorado", 
                "DC": "District of Columbia", "TX": "Texas", "FL": "Florida",
                "NY": "New York"}

    new_df['name'] = new_df['abbrev'].map(names_map) #  type(my_df['abbrev'])
    #we created a new column 'name' which was added to the existing dataframe
    # that had one column abbrev

    #breakpoint(): helps to stop and investigate in terminal up to the breakpoint()function

    return new_df