code: function (args, callback) {
          if (ternserver) {
            ternserver.request({
                query: {
                  type: "implementation",  //$NON-NLS-1$
                  file: args.meta.location,
                  end: args.params.offset,
                  guess: args.guess
                },
                files: args.files
              },
              function (error, impl) {
                if (error) {
                  callback({request: 'implementation', error: error.message, message: Messages['failedToComputeImpl']}); //$NON-NLS-1$
                }
                if (impl && impl.implementation && typeof impl.implementation.start === 'number' && typeof impl.implementation.end === "number") {
                  callback({request: 'implementation', implementation: impl.implementation}); //$NON-NLS-1$
                } else if (impl && impl.implementation && impl.implementation.origin) {
                  callback({request: 'implementation', implementation: impl.implementation}); //$NON-NLS-1$
                } else {
                  callback({request: 'implementation', implementation: null}); //$NON-NLS-1$
                }
              });
          } else {
            callback({request: 'implementation', message: Messages['failedToComputeImplNoServer']}); //$NON-NLS-1$
          }
        }
docs: /* implementation message handler