Added doctest to hash_map.py (TheAlgorithms#11105)

* Added doctest to heap.py

* Added doctest to hash_map.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Update hash_map.py

* Added doctest to hash_map.py

* Added doctest to hash_map.py

* Added doctest to detecting_english_programmatically.py

* Update detecting_english_programmatically.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>

Author: 3 people

data_structures/hashing/hash_map.py

@@ -242,6 +242,25 @@ def __delitem__(self, key: KEY) -> None:
             self._size_down()
 
     def __getitem__(self, key: KEY) -> VAL:
+        """
+        Returns the item at the given key
+
+        >>> hm = HashMap(5)
+        >>> hm._add_item(1, 10)
+        >>> hm.__getitem__(1)
+        10
+
+        >>> hm = HashMap(5)
+        >>> hm._add_item(10, -10)
+        >>> hm._add_item(20, -20)
+        >>> hm.__getitem__(20)
+        -20
+
+        >>> hm = HashMap(5)
+        >>> hm._add_item(-1, 10)
+        >>> hm.__getitem__(-1)
+        10
+        """
         for ind in self._iterate_buckets(key):
             item = self._buckets[ind]
             if item is None:
@@ -253,6 +272,20 @@ def __getitem__(self, key: KEY) -> VAL:
         raise KeyError(key)
 
     def __len__(self) -> int:
+        """
+        Returns the number of items present in hashmap
+
+        >>> hm = HashMap(5)
+        >>> hm._add_item(1, 10)
+        >>> hm._add_item(2, 20)
+        >>> hm._add_item(3, 30)
+        >>> hm.__len__()
+        3
+
+        >>> hm = HashMap(5)
+        >>> hm.__len__()
+        0
+        """
         return self._len
 
     def __iter__(self) -> Iterator[KEY]: