Create valid-parentheses.py

not the fastest but works for this one

valid-parentheses.py

@@ -0,0 +1,12 @@
+class Solution:
+    def isValid(self, s: str) -> bool:
+        stack = []
+        for letter in s:
+            if (stack[-1] if len(stack) > 0 else "") == self.other(letter):
+                stack.pop()
+            else:
+                stack.append(letter)
+        return len(stack) == 0
+
+    def other(self, ch: str) -> str:
+        return {"{": None, "}": "{", "(": None, ")": "(", "[": None, "]": "["}[ch]