Up to 10 and back

 x = []
for i in range(1,11):
    x.append(i)
print x
z = 0
for i in range(1,101):
    print x[z]
    if z == len(x)-1:
        x.reverse()
        z = 0
    z += 1

----------------------------------

up = 1
down = 10
x = 1
for i in range(1,51):
     print x,':',"up =",up, 'down =',down
     x += 1
     up += 1
     down -= 1
     if up >= 11:
         up = 1
     if down <= 0:
         down = 10
""" To switch between the up and down in a range of 20, so every 20 cycle repeates.

     if x <= 10:
         print "x is > 10:",up
     if x >= 12:
         print "x is < 10:",down
     if x == 19:
         x = 1
"""

#---------------------------


1 : up = 1 down = 10
2 : up = 2 down = 9
3 : up = 3 down = 8
4 : up = 4 down = 7
5 : up = 5 down = 6
6 : up = 6 down = 5
7 : up = 7 down = 4
8 : up = 8 down = 3
9 : up = 9 down = 2
10 : up = 10 down = 1
11 : up = 1 down = 10
12 : up = 2 down = 9
13 : up = 3 down = 8
14 : up = 4 down = 7
15 : up = 5 down = 6
16 : up = 6 down = 5
17 : up = 7 down = 4
18 : up = 8 down = 3
19 : up = 9 down = 2
20 : up = 10 down = 1
21 : up = 1 down = 10
22 : up = 2 down = 9
23 : up = 3 down = 8
24 : up = 4 down = 7
25 : up = 5 down = 6
26 : up = 6 down = 5
27 : up = 7 down = 4
28 : up = 8 down = 3
29 : up = 9 down = 2
30 : up = 10 down = 1
31 : up = 1 down = 10
32 : up = 2 down = 9
33 : up = 3 down = 8
34 : up = 4 down = 7
35 : up = 5 down = 6
36 : up = 6 down = 5
37 : up = 7 down = 4
38 : up = 8 down = 3
39 : up = 9 down = 2
40 : up = 10 down = 1
41 : up = 1 down = 10
42 : up = 2 down = 9
43 : up = 3 down = 8
44 : up = 4 down = 7
45 : up = 5 down = 6
46 : up = 6 down = 5
47 : up = 7 down = 4
48 : up = 8 down = 3
49 : up = 9 down = 2
50 : up = 10 down = 1