input: Write a python function to find all pairs in a sorted array that sum up to a target value.
  assert sum_pair([2, 4, 6, 9], 8) == [(2, 6)]
  assert sum_pair([1, 3, 5, 7, 9], 10) == [(1, 9), (3, 7)]
  assert sum_pair([1, 2, 3, 4, 5, 6], 7) == [(1, 6), (2, 5), (3, 4)]
  assert sum_pair([0, -1, 2, -3, 1], -1) == [(-3, 2), (-1, 0)]
output: def sum_pair(arr, target):
      pairs = []
      left, right = 0, len(arr) - 1
      
      while left < right:
          current_sum = arr[left] + arr[right]
          if current_sum == target:
              pairs.append((arr[left], arr[right]))
              left += 1
              right -= 1
          elif current_sum < target:
              left += 1
          else:
              right -= 1
      
      return pairs