[dataformat] Added missing doc and fixed doc related warnings

Also fixed import warnings

beat/backend/python/dataformat.py

@@ -26,9 +26,14 @@
 ###############################################################################
 
 
-"""Validation and parsing for dataformats"""
+"""
+==========
+dataformat
+==========
+
+Validation and parsing for dataformats
+"""
 
-import os
 import re
 import copy
 
@@ -230,7 +235,6 @@ class DataFormat(object):
             self.resolved.update(tmp)
             del self.resolved['#extends']  # avoids infinite recursion
 
-
     @property
     def name(self):
         """Returns the name of this object, either from the filename or composed
@@ -271,8 +275,8 @@ class DataFormat(object):
 
         Example:
 
-          To create an object respecting the data format from a JSON descriptor, use
-          the following technique:
+          To create an object respecting the data format from a JSON
+          descriptor, use the following technique:
 
           .. code-block:: python
 
@@ -335,6 +339,7 @@ class DataFormat(object):
 
     @property
     def valid(self):
+        """A boolean that indicates if this dataformat is valid or not"""
         return not bool(self.errors)
 
 
@@ -444,7 +449,8 @@ class DataFormat(object):
 
         Parameters:
 
-          indent (int): The number of indentation spaces at every indentation level
+          indent (int): The number of indentation spaces at every indentation
+            level
 
 
         Returns: