Leading underscores for objects intended only for internal use

[sadielbartholomew]

There are numerous functions marked, in their docstring, with the statement "This is an internal routine and is not used by the user." e.g:

cf-plot/cfplot/cfplot.py

Lines 3891 to 3894 in b0333d6

	def check_data(field=None, x=None, y=None):
	"""
	| check_data - check user input contour data is correct.
	| This is an internal routine and is not used by the user.

It would be ideal, for clarity to developers, to follow tradition and rename these all so they have leading underscores in their names.