code: function( data ){
  
              var bodies = this.getTargets()
                  ,dt = data.dt
                  ,bodyA
                  ,bodyB
                  ,collisions = []
                  ,ret
                  ,prevContacts = this.prevContacts || {}
                  ,contactList = {}
                  ,pairHash = Physics.util.pairHash
                  ,hash
                  ;
  
              for ( var j = 0, l = bodies.length; j < l; j++ ){
  
                  bodyA = bodies[ j ];
  
                  for ( var i = j + 1; i < l; i++ ){
  
                      bodyB = bodies[ i ];
  
                      ret = checkPair( bodyA, bodyB );
  
                      if ( ret instanceof Array ){
  
                          for ( var k = 0, r, ll = ret.length; k < ll; k++ ){
                              r = ret[k];
                              if ( r ){
                                  hash = pairHash( bodyA.uid, bodyB.uid );
                                  contactList[ hash ] = true;
                                  r.collidedPreviously = prevContacts[ hash ];
                                  collisions.push( r );
                              }
                          }
  
                      } else if ( ret ){
                          hash = pairHash( bodyA.uid, 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#checkAll( data )
  - data (Object): The event data
  
  Event callback to check all pairs of objects in the list for collisions