
    In an adaptive learning platform, identify the topic mastery level from a collection of student performance metrics where the student showed the lowest difficulty score (error rate). Each performance metric consists of a topic mastery level paired with its corresponding difficulty score, and you need to find the mastery level associated with the minimum difficulty score.
    

    
from operator import itemgetter

def index_minimum(test_list):
    """
    In an adaptive learning platform, identify the topic mastery level from a collection of student performance metrics where the student showed the lowest difficulty score (error rate). Each performance metric consists of a topic mastery level paired with its corresponding difficulty score, and you need to find the mastery level associated with the minimum difficulty score.
    

    """
from operator import itemgetter

def index_minimum(test_list):
    """
    In an adaptive learning platform, identify the topic mastery level from a collection of student performance metrics where the student showed the lowest difficulty score (error rate). Each performance metric consists of a topic mastery level paired with its corresponding difficulty score, and you need to find the mastery level associated with the minimum difficulty score.
    

    """
    res = min(test_list, key=itemgetter(1))[0]
    return res