Types of things that we expect from api

type Transcript = {
  type: 'Transcript';
  id: string;
  symbol: string;
  so_term: string; // is there a better name for it?
  slice: {
    location: {
      start: number;
      end: number;
      length: number; // is length the property of location or of the entity?
    };
    region: {
      name: string;
      strand: {
        code: Strand
      };
    };
  };
  exons: Exon[];
  cds: CDS | null;
};

// start and end positions are relative to chromosome (or other similar structure)
// relative_location is relative to transcript
type CDS = {
  start: number;
  end: number;
  relative_location: {
    start: number;
    end: number;
  }
}

type Exon = {
  id: string;
  slice: {
    location: {
      start: number,
      end: number
    },
    region: {
      ...
    }
  },
  relative_location: {
    start: number;
    end: number;
  }
};