irb(main):008:0> a['foo'].find(a:1).estimated_document_count
Traceback (most recent call last):
        5: from /home/w/.rbenv/versions/2.7/bin/irb:23:in `<main>'
        4: from /home/w/.rbenv/versions/2.7/bin/irb:23:in `load'
        3: from /home/w/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
        2: from (irb):8
        1: from /home/w/apps/ruby-driver/lib/mongo/collection/view/readable.rb:230:in `estimated_document_count'
ArgumentError (Cannot call estimated_document_count when querying with a filter)

irb(main):009:0> a['foo'].find.skip(4).estimated_document_count
=> 10
irb(main):010:0> a['foo'].find.limit(4).estimated_document_count
=> 10