Python: List Comprehension: Alternate

Write a function that takes two lists lst1 and lst2 and return another list whose elements are elements of lst1 and lst2 alternately. The input lists could be in different sizes.

alternate([1,2,3,4,5], [6,7,8]) -> [1,6,2,7,3,8,4,5]
alternate([1,2,3,4,5], []) -> [1,2,3,4,5]