class Solution(object):
    def reverseString(self, s):
        """
        :type s: List[str]
        :rtype: None Do not return anything, modify s in-place instead.
        """
        i,j=0, len(s)-1
       
        while i<j:
            temp= s[i]
            s[i]=s[j]
            s[j]=temp
            i+=1
            j-=1
        return(s)
