
    Given a list of customer transactions where each transaction is represented as a pair of customer ID and their associated fraud risk score, find the customer ID that corresponds to the lowest risk score. The risk score is a calculated probability between 0 and 1, where a lower score indicates a more legitimate transaction pattern.
    

    
from operator import itemgetter

def index_minimum(test_list):
    """
    Given a list of customer transactions where each transaction is represented as a pair of customer ID and their associated fraud risk score, find the customer ID that corresponds to the lowest risk score. The risk score is a calculated probability between 0 and 1, where a lower score indicates a more legitimate transaction pattern.
    

    """
from operator import itemgetter

def index_minimum(test_list):
    """
    Given a list of customer transactions where each transaction is represented as a pair of customer ID and their associated fraud risk score, find the customer ID that corresponds to the lowest risk score. The risk score is a calculated probability between 0 and 1, where a lower score indicates a more legitimate transaction pattern.
    

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