Adding TypeError verification

Author: krsm

Unitests/pystest_stdy/capitalize.py

@@ -6,6 +6,11 @@
 """
 
 
-def capitalize_string(str):
-    return str.capitalize()
+# it will receive a string and capitalize
+def capitalize_string(s):
+    if not isinstance(s, str):
+        raise TypeError('Please provide a string argument')
+    else:
+        return s.capitalize()
+