Write a function, longest_streak, that takes in the head of a linked list as an argument. The function should return the length of the longest consecutive streak of the same value within the list.
a = Node(5)
b = Node(5)
c = Node(7)
d = Node(7)
e = Node(7)
f = Node(6)
a.next = b
b.next = c
c.next = d
d.next = e
e.next = f
# 5 -> 5 -> 7 -> 7 -> 7 -> 6
longest_streak(a) # 3a = Node(3)
b = Node(3)
c = Node(3)
d = Node(3)
e = Node(9)
f = Node(9)
a.next = b
b.next = c
c.next = d
d.next = e
e.next = f
# 3 -> 3 -> 3 -> 3 -> 9 -> 9
longest_streak(a) # 4a = Node(9)
b = Node(9)
c = Node(1)
d = Node(9)
e = Node(9)
f = Node(9)
a.next = b
b.next = c
c.next = d
d.next = e
e.next = f
# 9 -> 9 -> 1 -> 9 -> 9 -> 9
longest_streak(a) # 3a = Node(5)
b = Node(5)
a.next = b
# 5 -> 5
longest_streak(a) # 2a = Node(4)
# 4
longest_streak(a) # 1longest_streak(None) # 0