Prefers the Entrez id, which names the gene exactly, and falls back to the
symbol. Exported because the token is what appears in source_id, so a
caller reconstructing a citation needs the same rule.
Prefers the Entrez id, which names the gene exactly, and falls back to the
symbol. Exported because the token is what appears in source_id, so a
caller reconstructing a citation needs the same rule.