Python 3.8 support

Author: krassowski

pylsp/_utils.py

@@ -262,6 +262,18 @@ class BlackFormatter(Formatter):
 formatters = {"ruff": RuffFormatter(), "black": BlackFormatter()}
 
 
+def removeprefix(text: str, prefix: str) -> str:
+    if text.startswith(prefix):
+        return text[len(prefix) :]
+    return text
+
+
+def removesuffix(text: str, suffix: str) -> str:
+    if suffix and text.endswith(suffix):
+        return text[: -len(suffix)]
+    return text
+
+
 def format_signature(signature: str, config: dict, signature_formatter: str) -> str:
     """Formats signature using ruff or black if either is available."""
     as_func = f"def {signature.strip()}:\n    pass"
@@ -270,9 +282,14 @@ def format_signature(signature: str, config: dict, signature_formatter: str) ->
     if formatter.is_installed:
         try:
             return (
-                formatter.format(as_func, line_length=line_length)
-                .removeprefix("def ")
-                .removesuffix(":\n    pass")
+                # TODO: replace with str.removeprefix and str.removesuffix
+                # once Python 3.8 support is no longer required
+                removesuffix(
+                    removeprefix(
+                        formatter.format(as_func, line_length=line_length), "def "
+                    ),
+                    ":\n    pass",
+                )
             )
         except subprocess.CalledProcessError as e:
             log.warning("Signature formatter failed %s", e)