import re
p = re.compile(r"""^                    # At the start of the string, ...
                   (?!                  # check if next characters are not...
                      www\.             # URLs starting with www.
                     |
                      (?:http|ftp)s?:// # URLs starting with http, https, ftp, ftps
                     |
                      [A-Za-z]:\\       # Local full paths starting with [drive_letter]:\  
                     |
                      //                # UNC locations starting with //
                   )                    # End of look-ahead check
                   .*                   # Martch up to the end of string""", re.X)
print(p.search("./about.html"));
print(p.search("//dub-server1/mynode"));

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