old_contents: """Module that defines binary insert operation using pluggable pivoting strategy."""
  
  
  def mutating_pluggable_binary_insert(choose_pivot, element, target, lower_index, upper_index):
      """Insert element into target list.
  
      Lower index is confirmed to be before, can be -1;
      Upper index is confirmed to be after, can be len(target).
  
      Pivot element is chosen by calling choose_pivot(lower_index, upper_index).
      TODO: Will there be pivoting strategies depending on more than just spread?
  
      In case of tie, element is inseted to upper part.
      Return None as this is operation mutates target.
      """
      spread = upper_index - lower_index
      assert spread > 0, "Binary insert encountered non-positive window size."
      if spread <= 1:
          target[upper_index:upper_index] = [element]
          return
      pivot_index = choose_pivot(lower_index, upper_index)
      if element < target[pivot_index]:
          mutating_pluggable_binary_insert(choose_pivot, element, target, lower_index, pivot_index)
      else:
          mutating_pluggable_binary_insert(choose_pivot, element, target, pivot_index, upper_index)
  
  
new_contents: """Module that defines binary insert operation using pluggable pivoting strategy."""
  
  
  def mutating_pluggable_binary_insert(choose_pivot, element, target, lower_index, upper_index):
      """Insert element into target list.
  
      Lower index is confirmed to be before, can be -1;
      Upper index is confirmed to be after, can be len(target).
  
      Pivot element is chosen by calling choose_pivot(lower_index, upper_index).
      TODO: Will there be pivoting strategies depending on more than just spread?
  
      In case of tie, element is inserted to upper part.
      Return None as this is operation mutates target.
      """
      spread = upper_index - lower_index
      assert spread > 0, "Binary insert encountered non-positive window size."
      if spread <= 1:
          target[upper_index:upper_index] = [element]
          return
      pivot_index = choose_pivot(lower_index, upper_index)
      if element < target[pivot_index]:
          mutating_pluggable_binary_insert(choose_pivot, element, target, lower_index, pivot_index)
      else:
          mutating_pluggable_binary_insert(choose_pivot, element, target, pivot_index, upper_index)
  
subject: Fix one typo