@@ -31,6 +31,7 @@ def test_dictionary():
     }
 
     assert isinstance(fruits_dictionary, dict)
+    assert not isinstance(fruits_dictionary, list)
 
     # You may access set elements by keys.
     assert fruits_dictionary['apple'] == 'green'
@@ -59,6 +60,7 @@ def test_dictionary():
 
     # The dict() constructor builds dictionaries directly from sequences of key-value pairs.
     dictionary_via_constructor = dict([('sape', 4139), ('guido', 4127), ('jack', 4098)])
+    assert {'a': 1, 'b': 2, 'c': 3} == dict([('a', 1), ('b', 2), ('c', 3)])
 
     assert dictionary_via_constructor['sape'] == 4139
     assert dictionary_via_constructor['guido'] == 4127
@@ -67,13 +69,17 @@ def test_dictionary():
     # In addition, dict comprehensions can be used to create dictionaries from arbitrary key
     # and value expressions:
     dictionary_via_expression = {x: x**2 for x in (2, 4, 6)}
+    xx = {x: (x + y) for x in range(2) for y in range(2)}
+    print(xx)
     assert dictionary_via_expression[2] == 4
     assert dictionary_via_expression[4] == 16
     assert dictionary_via_expression[6] == 36
 
     # When the keys are simple strings, it is sometimes easier to specify pairs using
     # keyword arguments.
     dictionary_for_string_keys = dict(sape=4139, guido=4127, jack=4098)
+
+    assert dict(xy = 1, yz = 2, xz = 3) == {'xy': 1, 'yz': 2, "xz": 3}
     assert dictionary_for_string_keys['sape'] == 4139
     assert dictionary_for_string_keys['guido'] == 4127
     assert dictionary_for_string_keys['jack'] == 4098
@@ -274,6 +274,8 @@ def test_list_comprehensions():
     vector = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
     flatten_vector = [num for elem in vector for num in elem]
     assert flatten_vector == [1, 2, 3, 4, 5, 6, 7, 8, 9]
+    test_flatten = [[2,3,4],[1,2,3],[4,3,2]]
+    assert [i for elm in test_flatten for i in elm] == [2,3,4,1,2,3,4,3,2]
 
 
 def test_nested_list_comprehensions():
 
@@ -137,6 +137,12 @@ def test_string_operators():
         'to have them joined together.'
     )
     assert text == 'Put several strings within parentheses to have them joined together.'
+    my_trial = (
+        "This is a new feature "
+        "Good to know this!"
+        "\n"
+    )
+    assert my_trial == "This is a new feature Good to know this!\n"
 
     # If you want to concatenate variables or a variable and a literal, use +:
     prefix = 'Py'
 
@@ -63,6 +63,11 @@ def test_tuples():
     assert len(singleton_tuple) == 1
     assert singleton_tuple == ('hello',)
 
+    my_singleton = 'abc',
+    assert my_singleton == ('abc', )
+    my_singleton2 = 'this ', 'is', 'new',
+    assert  my_singleton2 == ('this ', 'is', 'new', )
+
     # The following example is called tuple packing:
     packed_tuple = 12345, 54321, 'hello!'
 
 
@@ -42,3 +42,14 @@ def test_arithmetic_operators():
     assert 7 // 3 == 2
     assert 9 // 3 == 3
     assert isinstance(5 // 3, int)
+
+def test_my_arithetic_operators():
+    """my operators"""
+    # addition
+    assert 5 + 5 == 10
+    # subtraction
+    assert 90 - 90.0 == 0.0
+    assert isinstance(5 / 3, float)
+    assert isinstance(4 / 2, float)
+
+    assert 8 + 8 == 16