fix json_extract doctest

Author: TrevorBergeron

bigframes/bigquery/__init__.py

@@ -224,7 +224,7 @@ def json_extract(
 
         >>> s = bpd.Series(['{"class": {"students": [{"id": 5}, {"id": 12}]}}'])
         >>> bbq.json_extract(s, json_path="$.class")
-        0    "{\\\"students\\\":[{\\\"id\\\":5},{\\\"id\\\":12}]}"
+        0    {"students":[{"id":5},{"id":12}]}
         dtype: string
 
     Args:

bigframes/core/compile/compiled.py

@@ -322,8 +322,6 @@ def _to_ibis_expr(
         if not columns:
             return ibis.memtable([])
 
-        # Make sure all dtypes are the "canonical" ones for BigFrames. This is
-        # important for operations like UNION where the schema must match.
         table = self._table.select(columns)
         base_table = table
         if self._reduced_predicate is not None:
@@ -1031,8 +1029,6 @@ def _to_ibis_expr(
         # Make sure we don't have any unbound (deferred) columns.
         table = self._table.select(columns)
 
-        # Make sure all dtypes are the "canonical" ones for BigFrames. This is
-        # important for operations like UNION where the schema must match.
         table = table.select(table[column] for column in table.columns)
         base_table = table
         if self._reduced_predicate is not None: