added predecessor function to singly linked list
added delete function to singly linked list
updated singly
added doubly linked lists with basic functionality
updated singly tests
fixed singly tests
fixed issues in doubly
added test for singly deletion
added insertion into empty dll functionality
removed trailing whitespace
added tests for doubly-linked lists
small fixes in doubly
fixed some function names in the singly tests
added doubly test
updated singly test
updated singly test
updated doubly test
updated singly
updated singly test
actually added the tests back into singly. apparently you need to export them