remove unnecessary snippets

snippets/is_lower_case.md

@@ -1,19 +0,0 @@
----
-title: is_lower_case
-tags: string,utility,beginner
----
-
-Checks if a string is lower case.
-
-Convert the given string to lower case, using `str.lower()` and compare it to the original.
-
-```py
-def is_lower_case(string):
-  return string == string.lower()
-```
-
-```py
-is_lower_case('abc') # True
-is_lower_case('a3@$') # True
-is_lower_case('Ab4') # False
-```

snippets/is_upper_case.md

@@ -1,19 +0,0 @@
----
-title: is_upper_case
-tags: string,utility,beginner
----
-
-Checks if a string is upper case.
-
-Convert the given string to upper case, using `str.upper()` and compare it to the original.
-
-```py
-def is_upper_case(string):
-  return string == string.upper()
-```
-
-```py
-is_upper_case('ABC') # True
-is_upper_case('a3@$') # False
-is_upper_case('aB4') # False
-```