DOC: More coding conventions.

DEVELOPMENT.txt

@@ -58,7 +58,19 @@ Stylistic Guidelines
 
      cimport numpy as cnp # in Cython code
 
+ * When documenting array parameters, use ``image : (M, N) ndarray``,
+   ``image : (M, N, 3) ndarray`` and then refer to ``M`` and ``N`` in the
+   docstring.
  * Set up your editor to remove trailing whitespace.
+ * If a function name, say ``segment(...)``, has the same name as the file in
+   which it is implemented, name that file ``_segment.py`` so that it can still
+   be imported.
+ * Functions should support all input image dtypes.  Use utility functions such
+   as ``img_as_float`` to help convert to an appropriate type.  The output
+   format can be whatever is most efficient.  This allows us to string together
+   several functions into a pipeline, e.g.::
+
+     hough(canny(my_image))
 
 Test coverage
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