Please keep it simple!
class Solution(object):
def insert(self, intervals, newInterval):
"""
:type intervals: List[List[int]]
:type newInterval: List[int]
:rtype: List[List[int]]
"""
s, e = newInterval[0], newInterval[1]
left, right = [], []
for i in intervals:
if i[1]<s:
left.append(i)
elif e<i[0]:
right.append(i)
else:
s = min(s, i[0])
e = max(e, i[1])
return left+[[s,e]]+right