:: assoc-join
( ... assoc1 assoc2 quot: ( ... key value1 value2 -- ... newkey newvalue ) -- ... newassoc )
    assoc1 quot '[ over assoc2 at _ when* ] assoc-map ; inline

!!!!!!!!!!!!
! Examples !
!!!!!!!!!!!!

H{
    { "x" 7 }
    { "y" 3 }
}
H{
    { "x" 45 }
}
[ + ] assoc-join
  => H{
         { "x" 52 }
         { "y" 3 }
     }

!!!!!!!!!!!!!!

H{
    { "foo"
        H{
            { "attr1" 70 }
            { "attr2" "aiarht" }
        }
    }
}
H{
    { "foo"
        H{
            { "attr2" "oayrus" }
            { "attr3" "new" }
        }
    }
}
[ assoc-union ] assoc-join
  => H{
         { "foo"
             H{
                 { "attr1" 70 }
                 { "attr2" "oayrus" }
                 { "attr3" "new" }
             }
         }
     }