added some docstrings

cbutil/cpu_frequency.py

@@ -44,6 +44,18 @@ def read_frequency_from_file(file_path: str) -> float:
 
 
 def run_command(command: str) -> str:
+    """
+    Runs a shell command and returns its output.
+
+    Args:
+        command: The shell command to run.
+
+    Returns:
+        The output of the command as a string.
+
+    Raises:
+        ValueError: If there is an error running the shell command.
+    """
     try:
         result = subprocess.run(
             command,
@@ -58,6 +70,19 @@ def run_command(command: str) -> str:
 
 
 def filter_output(pattern: str, output: str) -> str:
+    """
+    Filters the output of a command using a regex pattern.
+
+    Args:
+        pattern: The regex pattern to search for.
+        output: The output of the command as a string.
+
+    Returns:
+        The first match for the regex pattern in the output.
+
+    Raises:
+        LookupError: If no match is found for the regex pattern.
+    """
     pattern = re.compile(pattern)
     match = pattern.search(output)
     if match: