Cannot form the union of more than two tables #926

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TypeError                                 Traceback (most recent call last)
~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/IPython/core/formatters.py in __call__(self, obj)
    700                 type_pprinters=self.type_printers,
    701                 deferred_pprinters=self.deferred_printers)
--> 702             printer.pretty(obj)
    703             printer.flush()
    704             return stream.getvalue()

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/IPython/lib/pretty.py in pretty(self, obj)
    392                         if cls is not object \
    393                                 and callable(cls.__dict__.get('__repr__')):
--> 394                             return _repr_pprint(obj, self, cycle)
    395 
    396             return _default_pprint(obj, self, cycle)

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/IPython/lib/pretty.py in _repr_pprint(obj, p, cycle)
    698     """A pprint that just redirects to the normal repr function."""
    699     # Find newlines and replace them with p.break_()
--> 700     output = repr(obj)
    701     lines = output.splitlines()
    702     with p.group():

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in __repr__(self)
    527         :rtype: str
    528         """
--> 529         return super().__repr__() if config['loglevel'].lower() == 'debug' else self.preview()
    530 
    531     def preview(self, limit=None, width=None):

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in preview(self, limit, width)
    531     def preview(self, limit=None, width=None):
    532         """ :return: a string of preview of the contents of the query. """
--> 533         return preview(self, limit, width)
    534 
    535     def _repr_html_(self):

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/preview.py in preview(query_expression, limit, width)
     11     if width is None:
     12         width = config['display.width']
---> 13     tuples = rel.fetch(limit=limit + 1, format="array")
     14     has_more = len(tuples) > limit
     15     tuples = tuples[:limit]

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/fetch.py in __call__(self, offset, limit, order_by, format, as_dict, squeeze, download_path, *attrs)
    190                 ret = return_values[0] if len(attrs) == 1 else return_values
    191         else:  # fetch all attributes as a numpy.record_array or pandas.DataFrame
--> 192             cur = self._expression.cursor(
    193                 as_dict=as_dict, limit=limit, offset=offset, order_by=order_by)
    194             heading = self._expression.heading

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in cursor(self, offset, limit, order_by, as_dict)
    511         if offset and limit is None:
    512             raise DataJointError('limit is required when offset is set')
--> 513         sql = self.make_sql()
    514         if order_by is not None:
    515             sql += ' ORDER BY ' + ', '.join(order_by)

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in make_sql(self, fields)
    111             distinct="DISTINCT " if distinct else "",
    112             fields=self.heading.as_sql(fields or self.heading.names),
--> 113             from_=self.from_clause(), where=self.where_clause())
    114 
    115     # --------- query operators -----------

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in from_clause(self)
     91             self._subquery_alias_count) if isinstance(src, QueryExpression)
     92             else src for src in self.support)
---> 93         clause = next(support)
     94         for s, left in zip(support, self._left):
     95             clause += ' NATURAL{left} JOIN {clause}'.format(

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in (.0)
     88 
     89     def from_clause(self):
---> 90         support = ('(' + src.make_sql() + ') as `$%x`' % next(
     91             self._subquery_alias_count) if isinstance(src, QueryExpression)
     92             else src for src in self.support)

~/anaconda3/envs/neural-data-kit/lib/python3.8/site-packages/datajoint/expression.py in make_sql(self)
    627             fields = arg1.primary_key
    628             return "({sql1}) UNION ({sql2})".format(
--> 629                 sql1=arg1.make_sql(fields),
    630                 sql2=arg2.make_sql(fields))
    631         # with secondary attributes, use union of left join with antijoin

TypeError: make_sql() takes 1 positional argument but 2 were given