docstr: Updates a node in Binary Index Tree (bit_tree) at given index in bit_tree. The given value 'val' is added to bit_tree[i] and all of its ancestors in tree. 
docstr_tok: ["Updates","a","node","in","Binary","Index","Tree","(","bit_tree",")","at","given","index","in","bit_tree",".","The","given","value","'val","'","is","added","to","bit_tree","[","i","]","and","all","of","its","ancestors","in","tree","."]
code: def update_bit(self, bit_tree, i, v):
      """
      Updates a node in Binary Index Tree (bit_tree) at given index in bit_tree. The given value 'val' is added to bit_tree[i] and all of its ancestors in tree.
      """
  
      # index in bit_ree[] is 1 more than the index in arr[]
      i += 1
  
      # Traverse all ancestors and add 'val'
      while i <= self.n:
          # Add 'val' to current node of bit_tree
          bit_tree[i] += v
  
          # Update index to that of parent in update View
          i += i & (-i)
  
label_desc: Use image node_id 3 for calling the Fenwick_Tree obj's underlying member method code with example usage: obj.update_bit(bit_tree, i, v) without return types