1, nums is List type:
nums.count (xxx) is the number of XXX in Nums;
nums.index (xxx, number) is the index of XXX in the List behind Number’s index in Nums

2, a [::-1] to find it from behind;
3、return False
4, STRS is list type: zip (*strs): #zip () function to use iterative objects as parameters, pack the corresponding elements in the object into each one, and then return to the group composed of these meta -groups List;

strs = ["flower","flow","flight"]
zip(*strs)
print(zip(*strs))
[('f', 'f', 'f'), ('l', 'l', 'l'), ('o', 'o', 'i'), ('w', 'w', 'g')]

5, set () merger:

for each in zip(*strs):
	print(set(each))
#
set(['f'])
set(['l'])
set(['i', 'o'])
set(['g', 'w'])

6. A = {{’)’: ’:’ (’(,’] ’:’: ’:’: ’:’: ’: {’ {’
is one -on -one and search is),],],} in A, a [‘’) ’] = (
7、l=[None]
l.pop () is one of the tails in the out L in POP;
At this time len (L) = 1;
L is the indexes, 0, 1 …
From the tail is from -1, -2 to the front