Write a method that removes the value of a node with index i from a singly-linked list.  Also, you must raise exceptions when necessary.

Write a method that removes the value of a node with index i from a singly-linked list.  Also, you must raise exceptions when necessary. 

You must NOT use any other methods that **you implemented** in the assignment (everything must be done inline). (In python Programming)

Consider the following class definition:

class SLLException(Exception): 
    """ 
    Custom exception class to be used by Singly Linked List 
    DO NOT CHANGE THIS CLASS IN ANY WAY 
    """ 
    pass

class SLNode:
    """
    Singly Linked List Node class
    DO NOT CHANGE THIS CLASS IN ANY WAY
    """
    def __init__(self, value: object) -> None:
        self._next = None
        self._value = value

class LinkedList:
    def __init__(self, start_list=None):
        """
        Initializes a new linked list with front and back sentinels
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        self._head = SLNode(None)
        self._tail = SLNode(None)
        self._head._next = self._tail

        # populate SLL with initial values (if provided)
        # before using this feature, implement add_back() method
        if start_list is not None:
            for value in start_list:
                self.add_back(value)

    def __str__(self) -> str:
        """
        Return content of singly linked list in human-readable form
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        out = 'SLL ['
        if self._head._next != self._tail:
            cur = self._head._next._next
            out = out + str(self._head._next._value)
            while cur != self._tail:
                out = out + ' -> ' + str(cur._value)
                cur = cur._next
        out = out + ']'
        return out

    def length(self) -> int:
        """
        Return the length of the linked list
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        length = 0
        cur = self._head
        while cur._next != self._tail:
            cur = cur._next
            length += 1
        return length

    def is_empty(self) -> bool:
        """
        Return True is list is empty, False otherwise
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        return self._head._next == self._tail

    # ------------------------------------------------------------------ # 

    def remove_at_index(self, index: int) -> None : 
        """ 
        TODO: Write this implementation 
        """ 
        return