def extract_categories_from_categories_column(categories_column):
    """ Extracts the set of all categories that appear in the specified categories column (pandas series)."""
    result = []
    for (index, categories_column_text) in categories_column.iteritems():
        for category in categories_column_text.split("|"):
            if category not in result:
                result.append(category)
    result.sort()
    return result