is_dash_case_file_name

stringtools.is_dash_case_file_name(argument)

Is true when argument is a string and is hyphen-delimited lowercase file name with extension.

>>> stringtools.is_dash_case_file_name('foo-bar')
True

Otherwise false:

>>> stringtools.is_dash_case_file_name('foo.bar.blah')
False

Returns true or false.