diff --git a/tables.py b/tables.py
index 2c0d204..cadf2d9 100644
--- a/tables.py
+++ b/tables.py
@@ -33,6 +33,10 @@ class RevisionField(ABC, Generic[T]):
         :param revisions: The set of revisions to compute the field from.
         Revisions are passed in chronological order, so use revisions[-1] to
         access the most recent revision in the set.
+
+        Implementations of extract should handle the case where revisions is
+        either a single revision (collapse-user=FALSE), or a full edit session
+        of contiguous edits by the same user (collapse-user=TRUE).
         """
         pass
 
diff --git a/wikiq b/wikiq
index 75d8b0d..f1582e9 100755
--- a/wikiq
+++ b/wikiq
@@ -32,7 +32,7 @@ from deltas import SequenceMatcher, SegmentMatcher
 
 import pyarrow as pa
 import pyarrow.parquet as pq
-import pyarrow.csv as pc
+import pyarrow.csv as pacsv
 
 
 class PersistMethod:
@@ -338,7 +338,7 @@ class WikiqParser:
         page_count = 0
         rev_count = 0
 
-        writer: Union[pq.ParquetWriter, pc.CSVWriter]
+        writer: Union[pq.ParquetWriter, pacsv.CSVWriter]
 
         schema = table.schema()
         schema = schema.append(pa.field('revert', pa.bool_(), nullable=True))
@@ -362,7 +362,7 @@ class WikiqParser:
         if self.output_parquet:
             writer = pq.ParquetWriter(self.output_file, schema, flavor='spark')
         else:
-            writer = pc.CSVWriter(self.output_file, schema, write_options=pc.WriteOptions(delimiter='\t'))
+            writer = pacsv.CSVWriter(self.output_file, schema, write_options=pacsv.WriteOptions(delimiter='\t'))
 
         regex_matches = {}