a list from lists

[mixo]

I have a list of lists (which are not of the same size but can be).
How can I join lists to for a new list with elements from
the list?

i.e. from,
   listOfList = [ [1,2,3],[4,5],[6,7,8,9]]

I want to get,
   NewList= [1,2,3,4,5,6,7,8,9]

The new list does not need to be in any particular order.