Merge pull request #78 from d70-t/opendap_optional_chunks

opendap driver: make chunks argument optional

intake_xarray/opendap.py

@@ -22,7 +22,7 @@ class OpenDapSource(DataSourceMixin):
     ----------
     urlpath: str
         Path to source file.
-    chunks: int or dict
+    chunks: None, int or dict
         Chunks is used to load the new dataset into dask
         arrays. ``chunks={}`` loads the dataset with dask using a single
         chunk for all arrays.
@@ -39,7 +39,7 @@ class OpenDapSource(DataSourceMixin):
     """
     name = 'opendap'
 
-    def __init__(self, urlpath, chunks, auth=None, xarray_kwargs=None, metadata=None,
+    def __init__(self, urlpath, chunks=None, auth=None, xarray_kwargs=None, metadata=None,
                  **kwargs):
         self.urlpath = urlpath
         self.chunks = chunks