17 def upgrade_15(old):  argument
24 def upgrade_16(old):  argument
34 def upgrade_17(old):  argument
41 def upgrade_18(old):  argument
48 def upgrade_19(old):  argument
55 def upgrade_20(old):  argument
62 def upgrade_20(old):  argument
69 def upgrade_21(old):  argument
76 def upgrade_22(old):  argument
85 def upgrade_23(old):  argument
96 def upgrade_24(old):  argument
104 def upgrade_25(old):  argument
111 def upgrade_26(old):  argument
118 def upgrade_27(old):  argument