Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],…] (si < ei), determine if a person could attend all meetings.

class Solution:
    def canAttendMeetings(self, intervals: List[List[int]]) -> bool:
        intervals.sort(key=lambda x: x[0])
        prev = None
        for interval in intervals:
            if prev and prev[1] > interval[0]:
                return False
            else:
                prev = interval
        return True