src/language-graphql/parser-graphql.js/parseComments
function parseComments(ast) {
  const comments = [];
  const startToken = ast.loc.startToken;
  let next = startToken.next;
  while (next.kind !== "<EOF>") {
    if (next.kind === "Comment") {
      Object.assign(next, {
        // The Comment token's column starts _after_ the `#`,
        // but we need to make sure the node captures the `#`
        column: next.column - 1
      });
      comments.push(next);
    }
    next = next.next;
  }

  return comments;
}