code: function( data ){
  
              var candidates = data.candidates
                  ,pair
                  ,targets = this.getTargets()
                  ,collisions = []
                  ,ret
                  ,prevContacts = this.prevContacts || {}
                  ,contactList = {}
                  ,pairHash = Physics.util.pairHash
                  ,hash
                  ;
  
              for ( var i = 0, l = candidates.length; i < l; ++i ){
  
                  pair = candidates[ i ];
  
                  if ( targets === this._world._bodies ||
                      // only check if the members are targeted by this behavior
                      (Physics.util.indexOf( targets, pair.bodyA ) > -1) &&
                      (Physics.util.indexOf( targets, pair.bodyB ) > -1)
                  ){
                      ret = checkPair( pair.bodyA, pair.bodyB );
  
                      if ( ret instanceof Array ){
  
                          for ( var j = 0, r, ll = ret.length; j < ll; j++ ){
                              r = ret[j];
                              if ( r ){
                                  hash = pairHash( pair.bodyA.uid, pair.bodyB.uid );
                                  contactList[ hash ] = true;
                                  r.collidedPreviously = prevContacts[ hash ];
                                  collisions.push( r );
                              }
                          }
  
                      } else if ( ret ){
                          hash = pairHash( pair.bodyA.uid, pair.bodyB.uid );
                          contactList[ hash ] = true;
                          ret.collidedPreviously = prevContacts[ hash ];
  
                          collisions.push( ret );
                      }
                  }
              }
  
              this.prevContacts = contactList;
  
              if ( collisions.length ){
  
                  this._world.emit( this.options.channel, {
                      collisions: collisions
                  });
              }
          }
docs: internal
  BodyCollisionDetectionBehavior#check( data )
  - data (Object): The event data
  
  Event callback to check pairs of objects that have been flagged by broad phase for possible collisions.