Function to merge sorted lists

[Edward C. Jones]

Has anyone written in C a merge function for sorted Python sequences? It 
should look like:
     merged_list, tail1, tail2 = merge(list1, list2)
where either tail1 or tail2 is []. Suppose tail1 is []. Then tail2 is a 
terminal sublist of list2, the last element of merged_list is the last 
element of list1, and merged_list + tail2 is the merger of list1 and 
list2. Similarly if tail2 is [].

This function would be useful for writing external merge sort programs.

Thanks,
Ed Jones