diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index ab1082d..cd7f5d6 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -346,8 +346,8 @@
 class SourceLoader(_LoaderBasics):
 
     def path_mtime(self, path):
-        """Optional method that returns the modification time for the specified
-        path.
+        """Optional method that returns the modification time (an int) for the
+        specified path, where path is a str.
 
         Implementing this method allows the loader to read bytecode files.
 
@@ -355,7 +355,7 @@
         raise NotImplementedError
 
     def set_data(self, path, data):
-        """Optional method which writes data to a file path.
+        """Optional method which writes data (bytes) to a file path (a str).
 
         Implementing this method allows for the writing of bytecode files.
 
diff --git a/Lib/importlib/abc.py b/Lib/importlib/abc.py
index 2f6cfa4..fa343f8 100644
--- a/Lib/importlib/abc.py
+++ b/Lib/importlib/abc.py
@@ -19,7 +19,8 @@
 
     @abc.abstractmethod
     def load_module(self, fullname):
-        """Abstract method which when implemented should load a module."""
+        """Abstract method which when implemented should load a module.
+        The fullname is a str."""
         raise NotImplementedError
 
 
@@ -29,7 +30,10 @@
 
     @abc.abstractmethod
     def find_module(self, fullname, path=None):
-        """Abstract method which when implemented should find a module."""
+        """Abstract method which when implemented should find a module.
+        The fullname is a str and the optional path is a str or None.
+        Returns a Loader object.
+        """
         raise NotImplementedError
 
 Finder.register(machinery.BuiltinImporter)
@@ -49,7 +53,7 @@
     @abc.abstractmethod
     def get_data(self, path):
         """Abstract method which when implemented should return the bytes for
-        the specified path."""
+        the specified path.  The path must be a str."""
         raise NotImplementedError
 
 
@@ -65,19 +69,19 @@
     @abc.abstractmethod
     def is_package(self, fullname):
         """Abstract method which when implemented should return whether the
-        module is a package."""
+        module is a package.  The fullname is a str.  Returns a bool."""
         raise NotImplementedError
 
     @abc.abstractmethod
     def get_code(self, fullname):
         """Abstract method which when implemented should return the code object
-        for the module"""
+        for the module.  The fullname is a str.  Returns a types.CodeType."""
         raise NotImplementedError
 
     @abc.abstractmethod
     def get_source(self, fullname):
         """Abstract method which should return the source code for the
-        module."""
+        module.  The fullname is a str.  Returns a str."""
         raise NotImplementedError
 
 InspectLoader.register(machinery.BuiltinImporter)
@@ -118,12 +122,14 @@
     """
 
     def path_mtime(self, path):
-        """Return the modification time for the path."""
+        """Return the (int) modification time for the path (str)."""
         raise NotImplementedError
 
     def set_data(self, path, data):
         """Write the bytes to the path (if possible).
 
+        Accepts a str path and data as bytes.
+
         Any needed intermediary directories are to be created. If for some
         reason the file cannot be written because of permissions, fail
         silently.
@@ -171,8 +177,8 @@
 
     @abc.abstractmethod
     def source_path(self, fullname):
-        """Abstract method which when implemented should return the path to the
-        source code for the module."""
+        """Abstract method.  Accepts a str module name and returns the path to
+        the source code for the module."""
         raise NotImplementedError
 
     def get_filename(self, fullname):
@@ -280,19 +286,19 @@
 
     @abc.abstractmethod
     def source_mtime(self, fullname):
-        """Abstract method which when implemented should return the
+        """Abstract method. Accepts a str filename and returns an int
         modification time for the source of the module."""
         raise NotImplementedError
 
     @abc.abstractmethod
     def bytecode_path(self, fullname):
-        """Abstract method which when implemented should return the path to the
-        bytecode for the module."""
+        """Abstract method. Accepts a str filename and returns the str pathname
+        to the bytecode for the module."""
         raise NotImplementedError
 
     @abc.abstractmethod
     def write_bytecode(self, fullname, bytecode):
-        """Abstract method which when implemented should attempt to write the
-        bytecode for the module, returning a boolean representing whether the
-        bytecode was written or not."""
+        """Abstract method.  Accepts a str filename and bytes object
+        representing the bytecode for the module.  Returns a boolean
+        representing whether the bytecode was written or not."""
         raise NotImplementedError