split functionality file across new module as was getting too long on its own. All functions remian the same, but imports will need to be updated.

functionality/hashing.py

@@ -0,0 +1,36 @@
+"""
+This file contains functions for taking hashes of data and files.
+
+Author(s): David Marchant
+"""
+
+from hashlib import sha256
+
+from core.correctness.vars import HASH_BUFFER_SIZE, SHA256
+from core.correctness.validation import check_type, valid_existing_file_path
+
+def _get_file_sha256(file_path):
+    sha256_hash = sha256()
+    
+    with open(file_path, 'rb') as file_to_hash:
+        while True:
+            buffer = file_to_hash.read(HASH_BUFFER_SIZE)
+            if not buffer:
+                break
+            sha256_hash.update(buffer)
+    
+    return sha256_hash.hexdigest()
+
+def get_file_hash(file_path:str, hash:str, hint:str=""):
+    check_type(hash, str, hint=hint)
+
+    valid_existing_file_path(file_path)
+
+    valid_hashes = {
+        SHA256: _get_file_sha256
+    }
+    if hash not in valid_hashes:
+        raise KeyError(f"Cannot use hash '{hash}'. Valid are "
+            f"'{list(valid_hashes.keys())}")
+
+    return valid_hashes[hash](file_path)