feat: replace dict get with dunder method

strings/bpe_tokenizer.py

@@ -7,7 +7,7 @@ import itertools
 from collections import OrderedDict
 
 
-def get_byte_pair_counts(ids: list[int]):
+def get_byte_pair_counts(ids: list[int]) -> dict:
     """Count consecutive byte-pairs of an encoded string.
 
     >>> ids = [73, 32, 97, 109, 32, 74, 111, 110, 83, 110, 111, 119, 46]
@@ -23,7 +23,7 @@ def get_byte_pair_counts(ids: list[int]):
     return counts
 
 
-def merge(ids: list[int], pair: tuple, idx: int):
+def merge(ids: list[int], pair: tuple, idx: int) -> list[int]:
     """Replace most occurring byte pair with new byte that is not used
     in the data. For utf-8 encoding, we start with 256 as the new byte
 
@@ -48,12 +48,12 @@ def merge(ids: list[int], pair: tuple, idx: int):
 class Tokenizer:
     """Tokenize a string using the byte-pair encoding algorithm"""
 
-    def __init__(self, num_merges: int = 20, verbose: bool = False):
+    def __init__(self, num_merges: int = 20, verbose: bool = False) -> None:
         self.num_merges = num_merges
         self.merges: dict = {}
         self.verbose = verbose
 
-    def encode(self, text: str):
+    def encode(self, text: str) -> list[int]:
         """Convert a string to tokens (bytes)
 
         >>> t = Tokenizer()
@@ -80,7 +80,7 @@ class Tokenizer:
         # start merging most frequently occurring byte pairs
         for i in range(num_merges):
             counts = get_byte_pair_counts(ids)
-            pair = max(counts, key=counts.get)
+            pair = max(counts, key=counts.__getitem__)
 
             if counts[pair] == 1:
                 continue
@@ -93,7 +93,7 @@ class Tokenizer:
 
         return ids
 
-    def decode(self, ids: list[int]):
+    def decode(self, ids: list[int]) -> str:
         """Convert a list of tokens to the original string
 
         >>> t = Tokenizer()