import re
x = "தமிழ்"
combining_marks_bmp = '\u0300-\u036F\u0483-\u0489\u0591-\u05BD\u05BF\u05C1\u05C2\u05C4\u05C5\u05C7\u0610-\u061A\u064B-\u065F\u0670\u06D6-\u06DC\u06DF-\u06E4\u06E7\u06E8\u06EA-\u06ED\u0711\u0730-\u074A\u07A6-\u07B0\u07EB-\u07F3\u0816-\u0819\u081B-\u0823\u0825-\u0827\u0829-\u082D\u0859-\u085B\u08E3-\u0903\u093A-\u093C\u093E-\u094F\u0951-\u0957\u0962\u0963\u0981-\u0983\u09BC\u09BE-\u09C4\u09C7\u09C8\u09CB-\u09CD\u09D7\u09E2\u09E3\u0A01-\u0A03\u0A3C\u0A3E-\u0A42\u0A47\u0A48\u0A4B-\u0A4D\u0A51\u0A70\u0A71\u0A75\u0A81-\u0A83\u0ABC\u0ABE-\u0AC5\u0AC7-\u0AC9\u0ACB-\u0ACD\u0AE2\u0AE3\u0B01-\u0B03\u0B3C\u0B3E-\u0B44\u0B47\u0B48\u0B4B-\u0B4D\u0B56\u0B57\u0B62\u0B63\u0B82\u0BBE-\u0BC2\u0BC6-\u0BC8\u0BCA-\u0BCD\u0BD7\u0C00-\u0C03\u0C3E-\u0C44\u0C46-\u0C48\u0C4A-\u0C4D\u0C55\u0C56\u0C62\u0C63\u0C81-\u0C83\u0CBC\u0CBE-\u0CC4\u0CC6-\u0CC8\u0CCA-\u0CCD\u0CD5\u0CD6\u0CE2\u0CE3\u0D01-\u0D03\u0D3E-\u0D44\u0D46-\u0D48\u0D4A-\u0D4D\u0D57\u0D62\u0D63\u0D82\u0D83\u0DCA\u0DCF-\u0DD4\u0DD6\u0DD8-\u0DDF\u0DF2\u0DF3\u0E31\u0E34-\u0E3A\u0E47-\u0E4E\u0EB1\u0EB4-\u0EB9\u0EBB\u0EBC\u0EC8-\u0ECD\u0F18\u0F19\u0F35\u0F37\u0F39\u0F3E\u0F3F\u0F71-\u0F84\u0F86\u0F87\u0F8D-\u0F97\u0F99-\u0FBC\u0FC6\u102B-\u103E\u1056-\u1059\u105E-\u1060\u1062-\u1064\u1067-\u106D\u1071-\u1074\u1082-\u108D\u108F\u109A-\u109D\u135D-\u135F\u1712-\u1714\u1732-\u1734\u1752\u1753\u1772\u1773\u17B4-\u17D3\u17DD\u180B-\u180D\u18A9\u1920-\u192B\u1930-\u193B\u1A17-\u1A1B\u1A55-\u1A5E\u1A60-\u1A7C\u1A7F\u1AB0-\u1ABE\u1B00-\u1B04\u1B34-\u1B44\u1B6B-\u1B73\u1B80-\u1B82\u1BA1-\u1BAD\u1BE6-\u1BF3\u1C24-\u1C37\u1CD0-\u1CD2\u1CD4-\u1CE8\u1CED\u1CF2-\u1CF4\u1CF8\u1CF9\u1DC0-\u1DF5\u1DFC-\u1DFF\u20D0-\u20F0\u2CEF-\u2CF1\u2D7F\u2DE0-\u2DFF\u302A-\u302F\u3099\u309A\uA66F-\uA672\uA674-\uA67D\uA69E\uA69F\uA6F0\uA6F1\uA802\uA806\uA80B\uA823-\uA827\uA880\uA881\uA8B4-\uA8C4\uA8E0-\uA8F1\uA926-\uA92D\uA947-\uA953\uA980-\uA983\uA9B3-\uA9C0\uA9E5\uAA29-\uAA36\uAA43\uAA4C\uAA4D\uAA7B-\uAA7D\uAAB0\uAAB2-\uAAB4\uAAB7\uAAB8\uAABE\uAABF\uAAC1\uAAEB-\uAAEF\uAAF5\uAAF6\uABE3-\uABEA\uABEC\uABED\uFB1E\uFE00-\uFE0F\uFE20-\uFE2F'
combining_marks_astral = '\uD805[\uDCB0-\uDCC3\uDDAF-\uDDB5\uDDB8-\uDDC0\uDDDC\uDDDD\uDE30-\uDE40\uDEAB-\uDEB7\uDF1D-\uDF2B]|\uD834[\uDD65-\uDD69\uDD6D-\uDD72\uDD7B-\uDD82\uDD85-\uDD8B\uDDAA-\uDDAD\uDE42-\uDE44]|\uD804[\uDC00-\uDC02\uDC38-\uDC46\uDC7F-\uDC82\uDCB0-\uDCBA\uDD00-\uDD02\uDD27-\uDD34\uDD73\uDD80-\uDD82\uDDB3-\uDDC0\uDDCA-\uDDCC\uDE2C-\uDE37\uDEDF-\uDEEA\uDF00-\uDF03\uDF3C\uDF3E-\uDF44\uDF47\uDF48\uDF4B-\uDF4D\uDF57\uDF62\uDF63\uDF66-\uDF6C\uDF70-\uDF74]|\uD81B[\uDF51-\uDF7E\uDF8F-\uDF92]|\uD81A[\uDEF0-\uDEF4\uDF30-\uDF36]|\uD82F[\uDC9D\uDC9E]|\uD800[\uDDFD\uDEE0\uDF76-\uDF7A]|\uD836[\uDE00-\uDE36\uDE3B-\uDE6C\uDE75\uDE84\uDE9B-\uDE9F\uDEA1-\uDEAF]|\uD802[\uDE01-\uDE03\uDE05\uDE06\uDE0C-\uDE0F\uDE38-\uDE3A\uDE3F\uDEE5\uDEE6]|\uD83A[\uDCD0-\uDCD6]|\uDB40[\uDD00-\uDDEF]'
letter = r'[^\W\d_]'
pat = re.compile(r'{}(?:{}|[{}])*'.format(letter, combining_marks_astral, combining_marks_bmp))
print( re.findall(pat, x) )

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