Implementation:

#The following implementation can be extended for other Segment tree problems as well.
class SegmentTree:
def __init__(self):
self.tree = None

#Function to build tree
def buildTree(self,List):
n = len(List)
self.tree = [0 for i in range(2*n)]

#Initialize leaf nodes
for i in range(n):
self.tree[i+n] = List[i]

#Calculate parents and build the tree
for i in range(n-1,0,-1):
self.tree[i] = self.tree[i<<1] + self.tree[i<<1 | 1]

#The function takes the new value and left and right indices as arguments and

#updates the nodes in the given range
def updateInRange(self, value, left, right):
n = len(self.tree)//2

for i in range(left+n, right+n+1):
#Update the leaf node
self.tree[i] += value

j = i
#Move upwards and update parents
while j>1:
self.tree[j>>1] = self.tree[j] + self.tree[j^1]
j >>= 1

#The function takes the left and right indices as arguments and returns the sum
#in the index range [left,right)
def sumInRange(self, left, right):
n = len(self.tree)//2
result = 0
left += n
right += n

#Add the current node to the sum iff its parent is not included in the same
#(resulting in faster computation of result)
while left<right:
#If left is odd then it means that it is the right child of it's parent
#and the interval includes only left and not it's parent. So, include
#this node to sum and move to the parent of it's next node.
#Similar condition is applied to right index.
if left&1:
result += self.tree[left]
left += 1
if right&1:
right -= 1
result += self.tree[right]

left >>= 1
right >>= 1

return result


def main():
segmentTree = SegmentTree()

#Sample test case
sampleList = [1,3,5,7,9,11]
segmentTree.buildTree(sampleList)

print("Array representation of tree :",segmentTree.tree)
print("Sum of elements in the interval [1,3] :",segmentTree.sumInRange(1,4))


if __name__ == "__main__":
main()