text: class Solution:
      def reverseString(self, s: List[str]) -> None:
          """
          Do not return anything, modify s in-place instead.
          
          Write a function that reverses a string. The input 
          string is given as an array of characters char[].
  
          Do not allocate extra space for another array, you must 
          do this by modifying the input array in-place with O(1) extra memory.
  
          You may assume all the characters consist of printable ascii characters.
          """
          
          lo, hi =0, len(s)-1
          while lo<hi:
              s[lo],s[hi]=s[hi],s[lo]
              lo+=1
              hi-=1