Replace the old code with the new unified version

Author: codingEzio

chap03_recursion/recursion_reverse_list_and_sring.py

@@ -0,0 +1,49 @@
+def reverse_sequence_recursion(sequence):
+    # e.g.
+    # type('yes')       <class 'str'>
+    # type([9, 7, 1])   <class 'list'>
+    # type((9, 7, 1))   <class 'tuple'>
+    seq_type = type(sequence)
+
+    # this type of operations are called 'reflection'
+    #   "a way of getting class names at runtime then crt objs of that class"
+    empty_seq = seq_type()
+
+    if sequence == empty_seq:
+        return empty_seq
+
+    # take [9, 7, 1] for example (a list of call frames)
+    #   [9, 7, 1]
+    #   [7, 1]
+    #   [1]
+    #   []
+    rest_reverse = reverse_sequence_recursion(sequence[1:])
+
+    # []      + []  PRODUCES [ ]
+    # [ ]     + [1] PRODUCES [1]
+    # [  1]   + [7] PRODUCES [1, 7]
+    # [  1 7] + [9] PRODUCES [1, 7, 9]
+    first = sequence[0:1]
+    # the left  side is the value being returned
+    # the right side is the value of `first`
+
+    return rest_reverse + first
+
+
+# references
+#   concept
+#       https://stackoverflow.com/a/37635/6273859
+#   concept with examples
+#   see more
+#       reflection in other languages
+#           https://en.wikipedia.org/wiki/Reflective_programming
+
+
+def main():
+    assert reverse_sequence_recursion([9, 7, 1]) == [1, 7, 9]
+    assert reverse_sequence_recursion((9, 7, 1)) == (1, 7, 9)
+    assert reverse_sequence_recursion("rust") == "tsur"
+
+
+if "__main__" == __name__:
+    main()