9 characters, and clashes with existing files.
33 def userNameToFileName(userName, existing=[], prefix="", suffix=""):  argument
37 	upper- and lower-case characters, and clashes with existing files.
41 		existing: A case-insensitive list of all existing file names.
131 	if fullName.lower() in existing:
132 		fullName = handleClash1(userName, existing, prefix, suffix)
136 def handleClash1(userName, existing=[], prefix="", suffix=""):  argument
138 	existing should be a case-insensitive list
139 	of all existing file names.
143 	>>> existing = ["a" * 5]
145 	>>> e = list(existing)
146 	>>> handleClash1(userName="A" * 5, existing=e,
151 	>>> e = list(existing)
153 	>>> handleClash1(userName="A" * 5, existing=e,
158 	>>> e = list(existing)
160 	>>> handleClash1(userName="A" * 5, existing=e,
179 		if fullName.lower() not in existing:
188 		finalName = handleClash2(existing, prefix, suffix)
192 def handleClash2(existing=[], prefix="", suffix=""):  argument
194 	existing should be a case-insensitive list
195 	of all existing file names.
199 	>>> existing = [prefix + str(i) + suffix for i in range(100)]
201 	>>> e = list(existing)
202 	>>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == (
206 	>>> e = list(existing)
208 	>>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == (
212 	>>> e = list(existing)
214 	>>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == (
226 		if fullName.lower() not in existing: