fix(agent): don't add blocks that contain only punctuation (#469)

Trailing punctuation blocks are of little to no value (imho). This PR
ensures that we don't add those blocks.

From:

```
Here is the image you requested: 
(image/png: B1A98152-A422-4B44-8FD9-D7C954E82D2A)
.
```

To:

```
Here is the image you requested: 
(image/png: B1A98152-A422-4B44-8FD9-D7C954E82D2A)
```

---------

Co-authored-by: Douglas Reid <doug@steamship.com>

Author: douglas-reid

src/steamship/agents/functional/output_parser.py

@@ -1,13 +1,20 @@
 import json
 import re
+import string
 from typing import Dict, List, Optional
 
 from steamship import Block, MimeTypes, Steamship
 from steamship.agents.schema import Action, AgentContext, FinishAction, OutputParser, Tool
 from steamship.data.tags.tag_constants import RoleTag
 
 
-# TODO(dougreid): extract shared bits from this and the ReACT output parser into a utility?
+def is_punctuation(text: str):
+    for c in text:
+        if c not in string.punctuation:
+            return False
+    return True
+
+
 class FunctionsBasedOutputParser(OutputParser):
 
     tools_lookup_dict: Optional[Dict[str, Tool]] = None
@@ -46,7 +53,12 @@ def _blocks_from_text(client: Steamship, text: str) -> List[Block]:
         block_id_regex = r"(?:(?:\[|\()?Block)?\(?([A-F0-9]{8}\-[A-F0-9]{4}\-[A-F0-9]{4}\-[A-F0-9]{4}\-[A-F0-9]{12})\)?(?:(\]|\)))?"
         remaining_text = last_response
         result_blocks: List[Block] = []
-        while remaining_text is not None and len(remaining_text) > 0:
+        while remaining_text is not None and len(remaining_text.strip()) > 0:
+
+            if is_punctuation(remaining_text.strip()):
+                remaining_text = ""
+                continue
+
             match = re.search(block_id_regex, remaining_text)
             if match:
                 pre_block_text = FunctionsBasedOutputParser._remove_block_prefix(

tests/steamship_tests/agents/test_function_agent_output_parser.py

@@ -16,5 +16,5 @@ def test_output_block_ids_are_converted(client: Steamship):
     result = output_formatter.parse(test_text, context)
 
     assert isinstance(result, FinishAction)
-    assert len(result.output) == 3
+    assert len(result.output) == 2
     assert result.output[1].id == block_id