A singly linked list implementation with several methods:

• append(value) -> Adds new value at the end of the list.
• prepend() -> Adds new value at the begining of the list.
• size() -> Returns the length of list.
• head() -> Returns the first item of the list.
• tail() -> Returns the last item of the list.
• at(index) -> Returns the value at the given index from list.
• pop() -> Remove the last item and return the value of removed item.
• contains(value) -> Returns true if the value is present in the list otherwise returns false.
• find(value) -> Returns the index of the given value if it present in the list.
• toString() -> Returns a string that represent the structure of the list.
• insertAt(value, index) -> Insert value at the given index.
• removeAt(index) -> Removes the value from the given index.