feat: add Network._get_node() and update executable to support node selection

Signed-off-by: Angelina <aceppaluni@gmail.com>

Author: aceppaluni

CHANGELOG.md

@@ -27,6 +27,8 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Added expiration_time, auto_renew_period, auto_renew_account, fee_schedule_key, kyc_key in `TokenCreateTransaction`, `TokenUpdateTransaction` classes
 - Added comprehensive Google-style docstrings to the `CustomFee` class and its methods in `custom_fee.py`.
 - docs: Add `docs/sdk_developers/project_structure.md` to explain repository layout and import paths.
+- Support selecting specific node account ID(s) for queries and transactions (#362)
+- Added `Network._get_node()` method and updated execution flow to use node selection (#362)
 
 ### Changed
 - chore: replaced hardcoded 'testnet' messages with environment network name

src/hiero_sdk_python/client/network.py

@@ -171,6 +171,21 @@ def _select_node(self) -> _Node:
         self._node_index = (self._node_index + 1) % len(self.nodes)
         self.current_node = self.nodes[self._node_index]
         return self.current_node
+    
+    def _get_node(self, account_id: AccountId) -> Optional[_Node]:
+        """
+        Get a node matching the given account ID.
+
+        Args:
+            account_id (AccountId): The account ID of the node to locate.
+
+        Returns:
+            Optional[_Node]: The matching node, or None if not found.
+        """
+        for node in self.nodes:
+            if node._account_id == account_id:
+                return node
+        return None
 
     def get_mirror_address(self) -> str:
         """

src/hiero_sdk_python/executable.py

@@ -183,7 +183,7 @@ def _execute(self, client: "Client"):
             )
 
             self.node_account_id = selected_node_account_id
-            node = client.network._select_node(self.node_account_id)
+            node = client.network._get_node(self.node_account_id)
 
             # Create a channel wrapper from the client's channel
             channel = node._get_channel()