seq 3 | x=<put some code here>

x=`seq 3`

$ unset x; shopt -s lastpipe; set +m; seq 3 | x=$(cat); echo "$x"
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3

x=$(seq 3)

#!/bin/bash
echo "hello" | { read -r var; echo "Read value: $var"; }
echo "After the pipeline exited, var contains: $var"

seq 3 | read -d '' x

$ seq 3 | { read -d '' x; echo "$x"; }
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< <(seq 3) read -r -d '' var

# load $x, echo it quoted, then unquoted.
seq 3 | { x=$(</dev/stdin) ; echo "$x" ; echo $x ; }

1
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1 2 3

seq 3 | { n=$(cat /dev/stdin) ; echo "$n" ; echo $n ; }