Add pydoc strings

etcdlib.py

 #!/usr/bin/env python3
+"""Library to connect to etcd and manage docker service information."""
 
 import time
 import etcd
 
 
 class Connection:
+    """A high-level connection to etcd.
 
+    Manages a connection to etcd, and provides high-level methods for
+    interacting with service records and related meta-data.
+
+    Args:
+        host (str): Hostname to connect to etcd on.
+        port (int): Port to connect to etcd on.
+        prefix (str): Etcd node under which the service information is stored.
+    """
 
     def __init__(self, host, port, prefix):
         self._client = etcd.Client(host=host, port=port)
 
 
     def wipe(self):
+        """Deletes all service entries and related structures in etcd."""
         self._delete('')
 
 
     def add_containers(self, new_containers):
+        """Writes the new containers' information to etcd."""
         for container in new_containers:
             name = container['name']
             print('Adding container %s' % name)
 
 
     def remove_containers(self, old_containers):
+        """Deletes the containers' entries from etcd."""
         for container in old_containers:
             name = container['name']
             print('Removing container %s' % name)
 
 
     def get_label(self, label):
+        """Gets a map of container names to values for the given label."""
         node = self._read_recursive('/labels/%s' % label)
         if node:
             return {child.key.split('/')[-1]: child.value for child in node.children}
 
 
     def wait_for_update(self):
+        """Waits for an update to occur.
+
+        When writing entries to etcd, a special _updated key is set to the
+        current unix timestamp. This method watches that key until it is
+        changed, blocking execution.
+        """
         original_time = self._read('/_updated')
         new_time = original_time