nl_tokens: Internal extend call . Performance abstraction to bypass all the argument shenanigans as we know we will only be extending two items at a time internally .
pl_tokens: function _extend ( a , b ) { forEach ( b , ( bVal , key ) => { let type = typeForExtend ( a ) ; <mask> ( type ) { case types . array : case types . object : if ( a [ key ] === undefined || a [ key ] === null ) a [ key ] = b [ key ] ; else if ( isExtendable ( a [ key ] , b [ key ] ) ) _extend ( a [ key ] , b [ key ] ) ; break ; case types . set : if ( ! a . has ( bVal ) ) a . add ( bVal ) ; break ; case types . map : if ( ! a . has ( key ) ) a . set ( key , bVal ) ; else { let aVal = a . get ( key ) ; if ( aVal === undefined || aVal === null ) a . set ( key , bVal ) ; else if ( isExtendable ( aVal , bVal ) ) _extend ( aVal , bVal ) ; } break ; } } ) ; return a ; }