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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def load_combo_catalog():
 """Load a union of the user and global catalogs for convenience"""

    user_dir = user_data_dir()
    global_dir = global_data_dir()
    desc = 'Generated from data packages found on your intake search path'
    cat_dirs = []
    if os.path.isdir(user_dir):
        cat_dirs.append(user_dir + '/*.yaml')
        cat_dirs.append(user_dir + '/*.yml')
    if os.path.isdir(global_dir):
        cat_dirs.append(global_dir + '/*.yaml')
        cat_dirs.append(global_dir + '/*.yml')
    for path_dir in conf.get('catalog_path', []):
        if path_dir != '':
            if not path_dir.endswith(('yaml', 'yml')):
                cat_dirs.append(path_dir + '/*.yaml')
                cat_dirs.append(path_dir + '/*.yml')
            else:
                cat_dirs.append(path_dir)

    return YAMLFilesCatalog(cat_dirs, name='builtin', description=desc)