split off requests and env handling

rplugin/python3/mrpy/env.py

@@ -0,0 +1,24 @@
+from dataclasses import dataclass
+from os import environ
+
+
+@dataclass
+class EnvVar:
+    """
+    Environment Variable fetcher for use in dataclass ``field(default_factory=...)``
+
+    >>> @dataclass
+    >>> class SomeDataclass:
+    ...     field_name: str = field(default_factory=EnvVar("SOME_VAR_NAME", "err msg"))
+
+    """
+
+    var_name: str
+    err_msg: str = ""
+
+    def __call__(self) -> str:
+        try:
+            return environ[self.var_name]
+        except KeyError as e:
+            e.add_note(self.err_msg)
+            raise