code: function forEach(declarations, reqName, callback) {
          var d;
          if (reqName === "*") {
              // Iterate over all declarations.
              for (d in declarations) {
                  callback.call(this, d);
              }
          } else if (reqName.charAt(reqName.length - 1) === "*") {
              // Iterate over uncapped `*` declarations.
              var baseName = reqName.substring(0, reqName.length - 1);
              for (d in declarations) {
                  if (d.indexOf(baseName) === 0) {
                      callback.call(this, d);
                  }
              }
          } else {
              // A single dependency iteration.
              if (declarations[reqName]) {
                  callback.call(this, reqName);
              } else {
                  error("Invalid dependency '" + reqName + "'");
              }
          }
      }
docs: Iterate over declarations, executing a callback function for each matched dependency.