src/common/parser-include-shebang.js/includeShebang
function includeShebang(text, ast) {
  if (!text.startsWith("#!")) {
    return;
  }

  const index = text.indexOf("\n");
  const shebang = text.slice(2, index);
  const comment = {
    type: "Line",
    value: shebang,
    range: [0, index],
    loc: {
      source: null,
      start: {
        line: 1,
        column: 0
      },
      end: {
        line: 1,
        column: index
      }
    }
  };

  ast.comments = [comment].concat(ast.comments);
}