panel and operator problem ?

i have in the draw function of a panel

a line to call an operator like

   <b>col = split.column()
    col.operator("myPrint", text="Export", icon='RENDER_STILL')</b>

and the operator is defined as let say

def myPrint ():
print(“Darn he Clicked Me!”)

but in latest built 626 it does not work anymore

can someone show how to make it work again

Thanks for any help

You have wrong operator definition:
then use:

col.operator("my_cool_operator", text="Export", icon='RENDER_STILL')

working again thanks

but in this old srcipt there was a call done to a function instead of a class
like shown in example

i mean is there another way to call a function may be
or it does not exist anymore from the col.operator( command ?