def fill_date(slice,col):
    """Fill in empty rows of a date column in a dataframe

    Parameters
    ----------
    slice : dataframe
        Name of the dataframe 
        
    col : string
        Name of date column that needs to be filled
        

    Returns
    -------
    slice : dataframe
        New dataframe with a filled date column
    """
    slice[col] = slice[col].ffill()
    return slice