fix: 改进代码

src/heurams/kernel/particles/__init__.py

@@ -1,4 +1,21 @@
 from .atom import Atom
 from .electron import Electron
 from .nucleon import Nucleon
-#from .orbital import Orbital
+from .placeholders import (
+    AtomPlaceholder,
+    NucleonPlaceholder,
+    ElectronPlaceholder,
+    orbital_placeholder,
+)
+
+# from .orbital import Orbital
+
+__all__ = [
+    "Atom",
+    "Electron",
+    "Nucleon",
+    "AtomPlaceholder",
+    "NucleonPlaceholder",
+    "ElectronPlaceholder",
+    "orbital_placeholder",
+]

src/heurams/kernel/particles/nucleon.py

@@ -13,9 +13,11 @@ class Nucleon:
 
     def __init__(self, ident, payload, common):
         self.ident = ident
-        env = {"payload": payload,
-               "default": config_var.get()['puzzles'],
-               "nucleon": (payload | common)}
+        env = {
+            "payload": payload,
+            "default": config_var.get()["puzzles"],
+            "nucleon": (payload | common),
+        }
         self.evalizer = Evalizer(environment=env)
         self.data: dict = self.evalizer(deepcopy((payload | common)))  # type: ignore