code: function (where) {
          if (where !== undefined) {
              if (where.gene !== undefined) {
                  get_gene(where);
                  return;
              } else {
                  if (where.species === undefined) {
                      where.species = genome_browser.species();
                  } else {
                      genome_browser.species(where.species);
                  }
                  if (where.chr === undefined) {
                      where.chr = genome_browser.chr();
                  } else {
                      genome_browser.chr(where.chr);
                  }
                  if (where.from === undefined) {
                      where.from = genome_browser.from();
                  } else {
                      genome_browser.from(where.from);
                  }
                  if (where.to === undefined) {
                      where.to = genome_browser.to();
                  } else {
                      genome_browser.to(where.to);
                  }
              }
          } else { // "where" is undef so look for gene or loc
              if (genome_browser.gene() !== undefined) {
                  get_gene({ species : genome_browser.species(),
                      gene    : genome_browser.gene()
                  });
                  return;
              } else {
                  where = {};
                  where.species = genome_browser.species();
                  where.chr     = genome_browser.chr();
                  where.from    = genome_browser.from();
                  where.to      = genome_browser.to();
              }
          }
  
          // Min is 0 by default or use the provided promise
          conf.min_coord
              .then (function (min) {
                  genome_browser.min(min);
                  if (!conf.max_coord) {
                      var url = ensembl_rest.url()
                          .endpoint("info/assembly/:species/:region_name")
                          .parameters({
                              species: where.species,
                              region_name: where.chr
                          });
  
                      conf.max_coord = ensembl_rest.call (url)
                          .then (function (resp) {
                              return resp.body.length;
                          });
                  }
                  return conf.max_coord;
              })
              .then (function (max) {
                  genome_browser.max(max);
                  genome_browser._start();
  
              });
      }
docs: We hijack parent's start method