[Cater Waiter & Sets Concept]: Better Differentiation of Emoji Examples in Introduction & About Files (#3991)

* Changed emoji examples in indtroduction to be more differentiated.

* Differentiated emoji examples in about.md doc as well.

* Change one more example to differentiate.

concepts/sets/about.md

@@ -34,12 +34,13 @@ While sets can be created in many different ways, the most straightforward const
 A `set` can be directly entered as a _set literal_ with curly `{}` brackets and commas between elements.
 Duplicates are silently omitted:
 
-```python
->>> one_element = {'😀'}
-{'😀'}
 
->>> multiple_elements = {'😀', '😃', '😄', '😁'}
-{'😀', '😃', '😄', '😁'}
+```python
+>>> one_element = {'➕'}
+{'➕'}
+
+>>> multiple_elements = {'➕', '🔻', '🔹', '🔆'}
+{'➕', '🔻', '🔹', '🔆'}
 
 >>> multiple_duplicates =  {'Hello!', 'Hello!', 'Hello!', 
                             '¡Hola!','Привіт!', 'こんにちは！', 
@@ -108,9 +109,9 @@ Remember: sets can hold different datatypes and _nested_ datatypes, but all `set
 
 ```python
 # Attempting to use a list for a set member throws a TypeError
->>> lists_as_elements = {['😅','🤣'], 
-                        ['😂','🙂','🙃'], 
-                        ['😜', '🤪', '😝']}
+>>> lists_as_elements = {['🌈','💦'], 
+                        ['☁️','⭐️','🌍'], 
+                        ['⛵️', '🚲', '🚀']}
 
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
@@ -118,9 +119,9 @@ TypeError: unhashable type: 'list'
 
 
 # Standard sets are mutable, so they cannot be hashed.
->>> sets_as_elements = {{'😅','🤣'}, 
-                        {'😂','🙂','🙃'}, 
-                        {'😜', '🤪', '😝'}}
+>>> sets_as_elements = {{'🌈','💦'}, 
+                        {'☁️','⭐️','🌍'}, 
+                        {'⛵️', '🚲', '🚀'}}
 
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
@@ -131,14 +132,15 @@ However, a  `set` of `sets` can be created via type `frozenset()`:
 
 ```python
 # Frozensets don't have a literal form.
->>> set_1 = frozenset({'😜', '😝', '🤪'})
->>> set_2 = frozenset({'😅', '🤣'})
->>> set_3 = frozenset({'😂', '🙂', '🙃'})
+>>> set_1 = frozenset({'🌈','💦'})
+>>> set_2 = frozenset({'☁️','⭐️','🌍'})
+>>> set_3 = frozenset({'⛵️', '🚲', '🚀'})
 
 >>> frozen_sets_as_elements = {set_1, set_2, set_3}
 >>> frozen_sets_as_elements
-{frozenset({'😜', '😝', '🤪'}), frozenset({'😅', '🤣'}), 
-frozenset({'😂', '🙂', '🙃'})}
+{frozenset({'⛵️', '🚀', '🚲'}),
+ frozenset({'🌈', '💦'}),
+ frozenset({'☁️', '⭐️', '🌍'})}
 ```
 
 

exercises/concept/cater-waiter/.docs/introduction.md

@@ -32,11 +32,11 @@ A `set` can be directly entered as a _set literal_ with curly `{}` brackets and
 Duplicates are silently omitted:
 
 ```python
->>> one_element = {'😀'}
-{'😀'}
+>>> one_element = {'➕'}
+{'➕'}
 
->>> multiple_elements = {'😀', '😃', '😄', '😁'}
-{'😀', '😃', '😄', '😁'}
+>>> multiple_elements = {'➕', '🔻', '🔹', '🔆'}
+{'➕', '🔻', '🔹', '🔆'}
 
 >>> multiple_duplicates =  {'Hello!', 'Hello!', 'Hello!', 
                             '¡Hola!','Привіт!', 'こんにちは！', 
@@ -91,9 +91,9 @@ Sets can hold different datatypes and _nested_ datatypes, but all `set` elements
 
 ```python
 # Attempting to use a list for a set member throws a TypeError
->>> lists_as_elements = {['😅','🤣'], 
-                        ['😂','🙂','🙃'], 
-                        ['😜', '🤪', '😝']}
+>>> lists_as_elements = {['🌈','💦'], 
+                        ['☁️','⭐️','🌍'], 
+                        ['⛵️', '🚲', '🚀']}
 
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
@@ -101,9 +101,9 @@ TypeError: unhashable type: 'list'
 
 
 # Standard sets are mutable, so they cannot be hashed.
->>> sets_as_elements = {{'😅','🤣'}, 
-                        {'😂','🙂','🙃'}, 
-                        {'😜', '🤪', '😝'}}
+>>> sets_as_elements = {{'🌈','💦'}, 
+                        {'☁️','⭐️','🌍'}, 
+                        {'⛵️', '🚲', '🚀'}}
 
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>