Secret handshake

practice/secret-handshake/secret_handshake.py

@@ -1,2 +1,39 @@
 def commands(binary_str):
-    pass
+    """
+    Decodes a binary string into a secret handshake.
+
+    The binary string represents a sequence of actions, where each bit corresponds
+    to an action from the list ['wink', 'double blink', 'close your eyes', 'jump'].
+    If the first bit of the binary string is 1, the sequence of actions is reversed.
+
+    Args:
+        binary_str (str): The binary string to decode. It should contain up to 5 characters.
+
+    Returns:
+        list: The decoded sequence of actions.
+
+    Raises:
+        ValueError: If the binary string contains characters other than '0' and '1',
+                    or if it is longer than 5 characters.
+
+    Examples:
+        >>> commands('101')
+        ['close your eyes', 'wink']
+    """
+    if any(c not in '01' for c in binary_str) or len(binary_str) > 5:
+        raise ValueError('Invalid binary string')
+
+    actions = ['wink', 'double blink', 'close your eyes', 'jump']
+    handshake = []
+
+    # Iterate over the bits in the binary string, in reverse order
+    for i in range(4):
+        # If the bit is '1', append the corresponding action to the handshake
+        if binary_str[::-1][i:i+1] == '1':
+            handshake.append(actions[i])
+
+    # If the first bit of the binary string is '1', reverse the handshake
+    if binary_str[0] == '1':
+        handshake.reverse()
+
+    return handshake