Some minor edits.

matcalc/__init__.py

@@ -0,0 +1 @@
+"""Calculators for materials properties."""

matcalc/base.py

@@ -1,15 +1,24 @@
-"""
-Define basic API.
-"""
+"""Define basic API."""
+from __future__ import annotations
+
 import abc
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from pymatgen.core import Structure
 
-from pymatgen.core import Structure
 
 class PropCalc(abc.ABCMeta):
-    """
-    API for a property calculator.
-    """
+    """API for a property calculator."""
 
     @abc.abstractmethod
     def calc(self, structure: Structure) -> dict:
-        pass
+        """
+        All PropCalc should implement a calc method that takes in a pymatgen structure and returns a dict. Note that
+        the method can return more than one property.
+
+        Args:
+            structure: Pymatgen structure.
+
+        Returns: {"prop name": value}
+        """

matcalc/phonon.py

@@ -1,18 +1,32 @@
-"""
-Phonon properties
-"""
+"""Phonon properties."""
+from __future__ import annotations
 
-from ase.calculators.calculator import Calculator
+from typing import TYPE_CHECKING
 
 from .base import PropCalc
 
+if TYPE_CHECKING:
+    from ase.calculators.calculator import Calculator
+
+
 class PhononCalc(PropCalc):
-    """
-    Calculator for phonon properties.
-    """
+    """Calculator for phonon properties."""
 
     def __init__(self, calculator: Calculator):
+        """
+        Args:
+            calculator: ASE Calculator to use.
+        """
         self.calculator = calculator
 
     def calc(self, structure) -> dict:
-        pass
+        """
+        All PropCalc should implement a calc method that takes in a pymatgen structure and returns a dict. Note that
+        the method can return more than one property.
+
+        Args:
+            structure: Pymatgen structure.
+
+        Returns: {"prop name": value}
+        """
+        return {}