Convert a filename with spaces

convert.py

import re
from copy import copy

def convertToDotted(stri):
	output = ''
	previous_char = None
	for char in stri:
		
		x = re.fullmatch(r'\w', char)
		
		umlaut_repl = {'ö':'oe','ü':'ue','ä':'ae','ß':'ss'}
		if char in umlaut_repl.keys():
			output += umlaut_repl[char]
		elif x:
			output += char
		elif char == ' ':
			if previous_char != ' ':
				output += '.'
		elif char in ['.','-']:
			output += char
			
		previous_char = copy(char)
	return output
	
if __name__ == '__main__':
	print(convertToDotted('Some file with spaces convörts - to some file without spaces!'))