code: function checkSpacing(side, leftToken, rightToken) {
              if (sourceCode.isSpaceBetweenTokens(leftToken, rightToken) !== mode[side]) {
                  const after = leftToken.value === "*";
                  const spaceRequired = mode[side];
                  const node = after ? leftToken : rightToken;
                  let messageId = "";
  
                  if (spaceRequired) {
                      messageId = side === "before" ? "missingBefore" : "missingAfter";
                  } else {
                      messageId = side === "before" ? "unexpectedBefore" : "unexpectedAfter";
                  }
  
                  context.report({
                      node,
                      messageId,
                      fix(fixer) {
                          if (spaceRequired) {
                              if (after) {
                                  return fixer.insertTextAfter(node, " ");
                              }
                              return fixer.insertTextBefore(node, " ");
                          }
                          return fixer.removeRange([leftToken.range[1], rightToken.range[0]]);
                      }
                  });
              }
          }
docs: Checks the spacing between two tokens before or after the star token.
  @param {string} side Either "before" or "after".
  @param {Token} leftToken `function` keyword token if side is "before", or
  star token if side is "after".
  @param {Token} rightToken Star token if side is "before", or identifier
  token if side is "after".
  @returns {void}