added swap case problem

swap_case.py

@@ -0,0 +1,49 @@
+
+'''
+You are given a string and your task is to swap cases.
+In other words, convert all lowercase letters to uppercase letters and vice versa.
+Www.HacToberFEST.diGItalOCean.com → wWW.hACtOBERfest.DIgiTALocEAN.COM
+Pythonist 2 → pYTHONIST 2
+
+
+Constraints
+0 < len(s) <= 1000
+Sample Input 0
+>>HackerRank.com presents "Pythonist 2".
+Sample Output 0
+>>hACKERrANK.COM PRESENTS "pYTHONIST 2".
+'''
+
+
+import re
+
+#[^a-zA-Z] means any character that IS NOT a-z OR A-Z
+regexp = re.compile('[^a-zA-Z]+')
+
+
+def swap_case(s):
+    #Check the length of a string
+    if len(s) < 1001:
+        newstring = ''
+        for a in s:
+            # check condition if word in a for loop is in upper case letter  then make it lower case
+            # and concat it with 'newstring' string
+            if a.isupper() == True:
+                newstring += a.lower()
+            # check condition if word in a for loop is in lower case letter  then make it upper case
+            # and concat it with 'newstring' string
+            if a.islower() == True:
+                newstring += a.upper()
+            #If a word is not found in a regular expression then concat it with 'newstring' string
+            if regexp.search(a):
+                newstring += a
+
+    else:
+        raise Exception("Charater length should be less than 100")
+    return newstring
+
+
+if __name__ == '__main__':
+    s = input('Enter your string here: ')
+    result = swap_case(s)
+    print(result)