Fix use of map for Python3
This fixed a wrong use of map
in the Boole handler that was causing the error reported in https://its.cern.ch/jira/browse/LHCBGAUSS-2365?focusedCommentId=3920221&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-3920221