This is the error it returns. I hope it helps.
Traceback (most recent call last):
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 102, in expand_string
self.strings[name])
KeyError: 'sep'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/Users/michi/anaconda/bin/bibcure", line 177, in <module>
main()
File "/Users/michi/anaconda/bin/bibcure", line 130, in main
bibtex = bibtexparser.loads(inputfile.read(), parser=parser)
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/__init__.py", line 48, in loads
return parser.parse(bibtex_str)
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bparser.py", line 147, in parse
self._expr.parseFile(bibtex_file_obj)
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibtexexpression.py", line 263, in parseFile
return self.main_expression.parseFile(file_obj, parseAll=True)
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 2163, in parseFile
return self.parseString(file_contents, parseAll)
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1622, in parseString
loc, tokens = self._parse( instring, 0 )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3919, in parseImpl
return super(ZeroOrMore, self).parseImpl(instring, loc, doActions)
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3858, in parseImpl
loc, tmptokens = self_expr_parse( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3530, in parseImpl
ret = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3395, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3530, in parseImpl
ret = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3395, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3395, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3919, in parseImpl
return super(ZeroOrMore, self).parseImpl(instring, loc, doActions)
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3858, in parseImpl
loc, tmptokens = self_expr_parse( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3395, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3717, in parseImpl
return self.expr._parse( instring, loc, doActions, callPreParse=False )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3395, in parseImpl
loc, exprtokens = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
loc,tokens = self.parseImpl( instring, preloc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 3530, in parseImpl
ret = e._parse( instring, loc, doActions )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1405, in _parseNoCache
tokens = fn( instring, tokensStart, retTokens )
File "/Users/michi/anaconda/lib/python3.6/site-packages/pyparsing.py", line 1049, in wrapper
ret = func(*args[limit[0]:])
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibtexexpression.py", line 260, in _string_expr_parse_action
return self._string_expr_parse_action_fun(s, l, t)
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bparser.py", line 184, in <lambda>
BibDataStringExpression.expression_if_needed(t)))
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bparser.py", line 178, in <lambda>
maybe_interpolate = lambda expr: as_text(expr)
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 223, in as_text
return text_string_or_expression.get_value()
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 184, in get_value
return ''.join([BibDataString.expand_string(s) for s in self.expr])
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 184, in <listcomp>
return ''.join([BibDataString.expand_string(s) for s in self.expr])
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 150, in expand_string
return string_or_bibdatastring.get_value()
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 131, in get_value
return self._bibdatabase.expand_string(self.name)
File "/Users/michi/anaconda/lib/python3.6/site-packages/bibtexparser/bibdatabase.py", line 104, in expand_string
raise(UndefinedString(name))
bibtexparser.bibdatabase.UndefinedString: 'sep'